Split the tests for clarity

bin/build-site.sh

@@ -120,6 +120,7 @@ node $TW5_BUILD_TIDDLYWIKI \
 	|| exit 1
 
 # /empty.html					Empty
+# /empty.hta					For Internet Explorer
 # /empty-external-core.html		External core empty
 # /tiddlywikicore-<version>.js	Core plugin javascript
 node $TW5_BUILD_TIDDLYWIKI \

boot/boot.js

@@ -316,25 +316,8 @@ $tw.utils.htmlDecode = function(s) {
 	return s.toString().replace(/&lt;/mg,"<").replace(/&nbsp;/mg,"\xA0").replace(/&gt;/mg,">").replace(/&quot;/mg,"\"").replace(/&amp;/mg,"&");
 };
 
-/*
+/** @deprecated Use window.location.hash instead.  */
-Get the browser location.hash. We don't use location.hash because of the way that Firefox auto-urldecodes it (see http://stackoverflow.com/questions/1703552/encoding-of-window-location-hash)
+$tw.utils.getLocationHash = () => window.location.hash;
-*/
-$tw.utils.getLocationHash = function() {
-	const href = window.location.href,
-		idx = href.indexOf("#");
-
-	if(idx === -1) {
-		return "#";
-	}
-
-	const afterHash = href.substring(idx + 1);
-	if(afterHash.startsWith("#") || afterHash.startsWith("%23")) {
-		// Special case: ignore location hash if it itself starts with a #
-		return "#";
-	}
-	return href.substring(idx);
-};
-
 
 /** @deprecated Pad a string to a given length with "0"s. Length defaults to 2 */
 $tw.utils.pad = function(value,length = 2) {
@@ -613,7 +596,7 @@ $tw.utils.evalGlobal = function(code,context,filename,sandbox,allowGlobals) {
 	// Compile the code into a function
 	var fn;
 	if($tw.browser) {
-		fn = Function("return " + code + "\n\n//# sourceURL=" + filename)(); // See https://github.com/TiddlyWiki/TiddlyWiki5/issues/6839
+		fn = window["eval"](code + "\n\n//# sourceURL=" + filename); // eslint-disable-line no-eval -- See https://github.com/TiddlyWiki/TiddlyWiki5/issues/6839
 	} else {
 		if(sandbox){
 			fn = vm.runInContext(code,sandbox,filename)

core-server/server/routes/get-tiddler-html.js

@@ -33,8 +33,8 @@ exports.handler = function(request,response,state) {
 		}
 		var text = state.wiki.renderTiddler(renderType,renderTemplate,{parseAsInline: true, variables: {currentTiddler: title}});
 
-		var headers = {"Content-Type": renderType};
+		// Naughty not to set a content-type, but it's the easiest way to ensure the browser will see HTML pages as HTML, and accept plain text tiddlers as CSS or JS
-		state.sendResponse(200,headers,text,"utf8");
+		state.sendResponse(200,{},text,"utf8");
 	} else {
 		response.writeHead(404);
 		response.end();

core-server/server/server.js

@@ -42,8 +42,6 @@ function Server(options) {
 	}
 	// Setup the default required plugins
 	this.requiredPlugins = this.get("required-plugins").split(',');
-	// Initialise CORS
-	this.corsEnable = this.get("cors-enable") === "yes";
 	// Initialise CSRF
 	this.csrfDisable = this.get("csrf-disable") === "yes";
 	// Initialize Gzip compression
@@ -263,13 +261,6 @@ Server.prototype.requestHandler = function(request,response,options) {
 	state.urlInfo = url.parse(request.url);
 	state.queryParameters = querystring.parse(state.urlInfo.query);
 	state.pathPrefix = options.pathPrefix || this.get("path-prefix") || "";
-	// Enable CORS
-	if(this.corsEnable) {
-		response.setHeader("Access-Control-Allow-Origin", "*");
-		response.setHeader("Access-Control-Allow-Headers", "*");
-		response.setHeader("Access-Control-Allow-Methods", "*");
-		response.setHeader("Access-Control-Expose-Headers", "*");
-	}
 	state.sendResponse = sendResponse.bind(self,request,response);
 	// Get the principals authorized to access this resource
 	state.authorizationType = options.authorizationType || this.methodMappings[request.method] || "readers";
@@ -294,12 +285,6 @@ Server.prototype.requestHandler = function(request,response,options) {
 		response.end();
 		return;
 	}
-	// Reply to OPTIONS
-	if(this.corsEnable && request.method === "OPTIONS") {
-		response.writeHead(204);
-		response.end();
-		return;
-	}
 	// Find the route that matches this path
 	var route = self.findMatchingRoute(request,state);
 	// Optionally output debug info

core/language/en-GB/ControlPanel.multids

@@ -6,7 +6,6 @@ Appearance/Caption: Appearance
 Appearance/Hint: Ways to customise the appearance of your TiddlyWiki.
 Basics/AnimDuration/Prompt: Animation duration
 Basics/AutoFocus/Prompt: Default focus field for new tiddlers
-Basics/AutoFocusEdit/Prompt: Default focus field for existing tiddlers
 Basics/Caption: Basics
 Basics/DefaultTiddlers/BottomHint: Use [[double square brackets]] for titles with spaces. Or you can choose to {{retain story ordering||$:/snippets/retain-story-ordering-button}}
 Basics/DefaultTiddlers/Prompt: Default tiddlers

core/language/en-GB/Draft.multids

@@ -1,4 +0,0 @@
-title: $:/language/Draft/
-
-Attribution: Draft of '<<draft-title>>' by {{$:/status/UserName}}
-Title: Draft of '<<draft-title>>'

core/language/en-GB/TiddlerInfo.multids

@@ -9,11 +9,6 @@ Advanced/ShadowInfo/NotShadow/Hint: The tiddler <$link to=<<infoTiddler>>><$text
 Advanced/ShadowInfo/Shadow/Hint: The tiddler <$link to=<<infoTiddler>>><$text text=<<infoTiddler>>/></$link> is a shadow tiddler
 Advanced/ShadowInfo/Shadow/Source: It is defined in the plugin <$link to=<<pluginTiddler>>><$text text=<<pluginTiddler>>/></$link>
 Advanced/ShadowInfo/OverriddenShadow/Hint: It is overridden by an ordinary tiddler
-Advanced/CascadeInfo/Heading: Cascade Details
-Advanced/CascadeInfo/Hint: These are the view template segments (tagged <<tag "$:/tags/ViewTemplate">>) using a cascade filter and their resulting template for the current tiddler.
-Advanced/CascadeInfo/Detail/View: View
-Advanced/CascadeInfo/Detail/ActiveCascadeFilter: Active cascade filter
-Advanced/CascadeInfo/Detail/Template: Template
 Fields/Caption: Fields
 List/Caption: List
 List/Empty: This tiddler does not have a list

core/modules/background-actions.js

@@ -1,106 +0,0 @@
-/*\
-title: $:/core/modules/background-actions.js
-type: application/javascript
-module-type: global
-\*/
-
-"use strict";
-
-class BackgroundActionDispatcher {
-	constructor(filterTracker, wiki) {
-		this.filterTracker = filterTracker;
-		this.wiki = wiki;
-		this.nextTrackedFilterId = 1;
-		this.trackedFilters = new Map(); // Use Map for better key management
-
-		this.filterTracker.track({
-			filterString: "[all[tiddlers+shadows]tag[$:/tags/BackgroundAction]!is[draft]]",
-			fnEnter: title => this.trackFilter(title),
-			fnLeave: (title, enterValue) => this.untrackFilter(enterValue),
-			fnChange: (title, enterValue) => {
-				this.untrackFilter(enterValue);
-				return this.trackFilter(title);
-			},
-			fnProcess: changes => this.process(changes)
-		});
-	}
-
-	trackFilter(title) {
-		const tiddler = this.wiki.getTiddler(title);
-		const id = this.nextTrackedFilterId++;
-		const tracker = new BackgroundActionTracker({
-			wiki: this.wiki,
-			title,
-			trackFilter: tiddler.fields["track-filter"],
-			actions: tiddler.fields.text
-		});
-		this.trackedFilters.set(id, tracker);
-		return id;
-	}
-
-	untrackFilter(enterValue) {
-		const tracker = this.trackedFilters.get(enterValue);
-		if(tracker) {
-			tracker.destroy();
-		}
-		this.trackedFilters.delete(enterValue);
-	}
-
-	process(changes) {
-		for(const tracker of this.trackedFilters.values()) {
-			tracker.process(changes);
-		}
-	}
-}
-
-class BackgroundActionTracker {
-	constructor({wiki, title, trackFilter, actions}) {
-		this.wiki = wiki;
-		this.title = title;
-		this.trackFilter = trackFilter;
-		this.actions = actions;
-		this.filterTracker = new $tw.FilterTracker(this.wiki);
-		this.hasChanged = false;
-		this.trackerID = this.filterTracker.track({
-			filterString: this.trackFilter,
-			fnEnter: () => { this.hasChanged = true; },
-			fnLeave: () => { this.hasChanged = true; },
-			fnProcess: changes => {
-				if(this.hasChanged) {
-					this.hasChanged = false;
-					console.log("Processing background action", this.title);
-					const tiddler = this.wiki.getTiddler(this.title);
-					let doActions = true;
-					if(tiddler && tiddler.fields.platforms) {
-						doActions = false;
-						const platforms = $tw.utils.parseStringArray(tiddler.fields.platforms);
-						if(($tw.browser && platforms.includes("browser")) || ($tw.node && platforms.includes("node"))) {
-							doActions = true;
-						}
-					}
-					if(doActions) {
-						this.wiki.invokeActionString(
-							this.actions,
-							null,
-							{
-								currentTiddler: this.title
-							},{
-								parentWidget: $tw.rootWidget
-							}
-						);
-					}
-				}
-			}
-		});
-	}
-
-	process(changes) {
-		this.filterTracker.handleChangeEvent(changes);
-	}
-
-	destroy() {
-		this.filterTracker.untrack(this.trackerID);
-	}
-}
-
-exports.BackgroundActionDispatcher = BackgroundActionDispatcher;

core/modules/config.js

@@ -2,6 +2,9 @@
 title: $:/core/modules/config.js
 type: application/javascript
 module-type: config
+
+Core configuration constants
+
 \*/
 
 "use strict";

core/modules/deserializers.js

@@ -2,6 +2,9 @@
 title: $:/core/modules/deserializers.js
 type: application/javascript
 module-type: tiddlerdeserializer
+
+Functions to deserialise tiddlers from a block of text
+
 \*/
 
 "use strict";
@@ -34,6 +37,12 @@ exports["application/json"] = function(text,fields) {
 	return results;
 };
 
+/*
+Parse an HTML file into tiddlers. There are three possibilities:
+# A TiddlyWiki classic HTML file containing `text/x-tiddlywiki` tiddlers
+# A TiddlyWiki5 HTML file containing `text/vnd.tiddlywiki` tiddlers
+# An ordinary HTML file
+*/
 exports["text/html"] = function(text,fields) {
 	var results = [];
 	// Check if we've got an old-style store area
@@ -51,11 +60,11 @@ exports["text/html"] = function(text,fields) {
 		results.push.apply(results,deserializeNewStoreArea(text,newStoreAreaMarkerRegExp.lastIndex,newStoreAreaMatch[1],fields));
 		newStoreAreaMatch = newStoreAreaMarkerRegExp.exec(text);
 	}
-
+	// Return if we had either an old-style or a new-style store area
 	if(storeAreaMatch || haveHadNewStoreArea) {
 		return results;
 	}
-
+	// Otherwise, check whether we've got an encrypted file
 	var encryptedStoreArea = $tw.utils.extractEncryptedStoreArea(text);
 	if(encryptedStoreArea) {
 		// If so, attempt to decrypt it using the current password
@@ -115,18 +124,30 @@ function deserializeStoreArea(text,storeAreaEnd,isTiddlyWiki5,fields) {
 	return results;
 }
 
-var deserializeTiddlerDiv = function(text) {
+/*
+Utility function to parse an old-style tiddler DIV in a *.tid file. It looks like this:
+
+<div title="Title" creator="JoeBloggs" modifier="JoeBloggs" created="201102111106" modified="201102111310" tags="myTag [[my long tag]]">
+<pre>The text of the tiddler (without the expected HTML encoding).
+</pre>
+</div>
+
+Note that the field attributes are HTML encoded, but that the body of the <PRE> tag is not encoded.
+
+When these tiddler DIVs are encountered within a TiddlyWiki HTML file then the body is encoded in the usual way.
+*/
+var deserializeTiddlerDiv = function(text /* [,fields] */) {
 	// Slot together the default results
 	var result = {};
 	if(arguments.length > 1) {
 		for(var f=1; f<arguments.length; f++) {
 			var fields = arguments[f];
 			for(var t in fields) {
-				result[t] = fields[t];
+				result[t] = fields[t];		
 			}
 		}
 	}
-
+	// Parse the DIV body
 	var startRegExp = /^\s*<div\s+([^>]*)>(\s*<pre>)?/gi,
 		endRegExp,
 		match = startRegExp.exec(text);

core/modules/editor/engines/framed.js

@@ -2,6 +2,9 @@
 title: $:/core/modules/editor/engines/framed.js
 type: application/javascript
 module-type: library
+
+Text editor engine based on a simple input or textarea within an iframe. This is done so that the selection is preserved even when clicking away from the textarea
+
 \*/
 
 "use strict";
@@ -53,7 +56,7 @@ function FramedEngine(options) {
 	} else {
 		this.domNode.value = this.value;
 	}
-
+	// Set the attributes
 	if(this.widget.editType && this.widget.editTag !== "textarea") {
 		this.domNode.setAttribute("type",this.widget.editType);
 	}
@@ -75,7 +78,7 @@ function FramedEngine(options) {
 	if(this.widget.isDisabled === "yes") {
 		this.domNode.setAttribute("disabled",true);
 	}
-
+	// Copy the styles from the dummy textarea
 	this.copyStyles();
 	// Add event listeners
 	$tw.utils.addEventListeners(this.domNode,[
@@ -96,10 +99,13 @@ function FramedEngine(options) {
 			{name: "click",handlerObject: this.widget,handlerMethod: "handleClickEvent"}
 		]);
 	}
-
+	// Insert the element into the DOM
 	this.iframeDoc.body.appendChild(this.domNode);
 }
 
+/*
+Copy styles from the dummy text area to the textarea in the iframe
+*/
 FramedEngine.prototype.copyStyles = function() {
 	// Copy all styles
 	$tw.utils.copyStyles(this.dummyTextArea,this.domNode);
@@ -121,11 +127,14 @@ FramedEngine.prototype.setText = function(text,type) {
 		if(this.domNode.ownerDocument.activeElement !== this.domNode) {
 			this.updateDomNodeText(text);
 		}
-
+		// Fix the height if needed
 		this.fixHeight();
 	}
 };
 
+/*
+Update the DomNode with the new text
+*/
 FramedEngine.prototype.updateDomNodeText = function(text) {
 	try {
 		this.domNode.value = text;
@@ -134,10 +143,16 @@ FramedEngine.prototype.updateDomNodeText = function(text) {
 	}
 };
 
+/*
+Get the text of the engine
+*/
 FramedEngine.prototype.getText = function() {
 	return this.domNode.value;
 };
 
+/*
+Fix the height of textarea to fit content
+*/
 FramedEngine.prototype.fixHeight = function() {
 	// Make sure styles are updated
 	this.copyStyles();
@@ -157,6 +172,9 @@ FramedEngine.prototype.fixHeight = function() {
 	}
 };
 
+/*
+Focus the engine node
+*/
 FramedEngine.prototype.focus  = function() {
 	if(this.domNode.focus) {
 		this.domNode.focus();
@@ -166,12 +184,18 @@ FramedEngine.prototype.focus  = function() {
 	}
 };
 
+/*
+Handle a focus event
+*/
 FramedEngine.prototype.handleFocusEvent = function(event) {
 	if(this.widget.editCancelPopups) {
 		$tw.popup.cancel(0);
 	}
 };
 
+/*
+Handle a keydown event
+ */
 FramedEngine.prototype.handleKeydownEvent = function(event) {
 	if ($tw.keyboardManager.handleKeydownEvent(event, {onlyPriority: true})) {
 		return true;
@@ -180,11 +204,17 @@ FramedEngine.prototype.handleKeydownEvent = function(event) {
 	return this.widget.handleKeydownEvent(event);
 };
 
+/*
+Handle a click
+*/
 FramedEngine.prototype.handleClickEvent = function(event) {
 	this.fixHeight();
 	return true;
 };
 
+/*
+Handle a dom "input" event which occurs when the text has changed
+*/
 FramedEngine.prototype.handleInputEvent = function(event) {
 	this.widget.saveChanges(this.getText());
 	this.fixHeight();
@@ -194,6 +224,9 @@ FramedEngine.prototype.handleInputEvent = function(event) {
 	return true;
 };
 
+/*
+Create a blank structure representing a text operation
+*/
 FramedEngine.prototype.createTextOperation = function() {
 	var operation = {
 		text: this.domNode.value,
@@ -209,6 +242,9 @@ FramedEngine.prototype.createTextOperation = function() {
 	return operation;
 };
 
+/*
+Execute a text operation
+*/
 FramedEngine.prototype.executeTextOperation = function(operation) {
 	// Perform the required changes to the text area and the underlying tiddler
 	var newText = operation.text;

core/modules/editor/engines/simple.js

@@ -2,6 +2,9 @@
 title: $:/core/modules/editor/engines/simple.js
 type: application/javascript
 module-type: library
+
+Text editor engine based on a simple input or textarea tag
+
 \*/
 
 "use strict";
@@ -27,7 +30,7 @@ function SimpleEngine(options) {
 	} else {
 		this.domNode.value = this.value;
 	}
-
+	// Set the attributes
 	if(this.widget.editType && this.widget.editTag !== "textarea") {
 		this.domNode.setAttribute("type",this.widget.editType);
 	}
@@ -52,7 +55,7 @@ function SimpleEngine(options) {
 	if(this.widget.isDisabled === "yes") {
 		this.domNode.setAttribute("disabled",true);
 	}
-
+	// Add an input event handler
 	$tw.utils.addEventListeners(this.domNode,[
 		{name: "focus", handlerObject: this, handlerMethod: "handleFocusEvent"},
 		{name: "input", handlerObject: this, handlerMethod: "handleInputEvent"}
@@ -62,16 +65,22 @@ function SimpleEngine(options) {
 	this.widget.domNodes.push(this.domNode);
 }
 
+/*
+Set the text of the engine if it doesn't currently have focus
+*/
 SimpleEngine.prototype.setText = function(text,type) {
 	if(!this.domNode.isTiddlyWikiFakeDom) {
 		if(this.domNode.ownerDocument.activeElement !== this.domNode || text === "") {
 			this.updateDomNodeText(text);
 		}
-
+		// Fix the height if needed
 		this.fixHeight();
 	}
 };
 
+/*
+Update the DomNode with the new text
+*/
 SimpleEngine.prototype.updateDomNodeText = function(text) {
 	try {
 		this.domNode.value = text;
@@ -80,10 +89,16 @@ SimpleEngine.prototype.updateDomNodeText = function(text) {
 	}
 };
 
+/*
+Get the text of the engine
+*/
 SimpleEngine.prototype.getText = function() {
 	return this.domNode.value;
 };
 
+/*
+Fix the height of textarea to fit content
+*/
 SimpleEngine.prototype.fixHeight = function() {
 	// If .editRows is initialised, it takes precedence
 	if((this.widget.editTag === "textarea") && !this.widget.editRows) {
@@ -99,6 +114,9 @@ SimpleEngine.prototype.fixHeight = function() {
 	}
 };
 
+/*
+Focus the engine node
+*/
 SimpleEngine.prototype.focus = function() {
 	if(this.domNode.focus) {
 		this.domNode.focus();
@@ -108,6 +126,9 @@ SimpleEngine.prototype.focus = function() {
 	}
 };
 
+/*
+Handle a dom "input" event which occurs when the text has changed
+*/
 SimpleEngine.prototype.handleInputEvent = function(event) {
 	this.widget.saveChanges(this.getText());
 	this.fixHeight();
@@ -117,6 +138,9 @@ SimpleEngine.prototype.handleInputEvent = function(event) {
 	return true;
 };
 
+/*
+Handle a dom "focus" event
+*/
 SimpleEngine.prototype.handleFocusEvent = function(event) {
 	if(this.widget.editCancelPopups) {
 		$tw.popup.cancel(0);
@@ -132,10 +156,16 @@ SimpleEngine.prototype.handleFocusEvent = function(event) {
 	return true;
 };
 
+/*
+Create a blank structure representing a text operation
+*/
 SimpleEngine.prototype.createTextOperation = function() {
 	return null;
 };
 
+/*
+Execute a text operation
+*/
 SimpleEngine.prototype.executeTextOperation = function(operation) {
 };
 

core/modules/editor/factory.js

@@ -2,12 +2,16 @@
 title: $:/core/modules/editor/factory.js
 type: application/javascript
 module-type: library
+
+Factory for constructing text editor widgets with specified engines for the toolbar and non-toolbar cases
+
 \*/
 
 "use strict";
 
 var DEFAULT_MIN_TEXT_AREA_HEIGHT = "100px"; // Minimum height of textareas in pixels
 
+// Configuration tiddlers
 var HEIGHT_MODE_TITLE = "$:/config/TextEditor/EditorHeight/Mode";
 var ENABLE_TOOLBAR_TITLE = "$:/config/TextEditor/EnableToolbar";
 
@@ -44,8 +48,8 @@ function editTextWidgetFactory(toolbarEngine,nonToolbarEngine) {
 			this.toolbarNode = this.document.createElement("div");
 			this.toolbarNode.className = "tc-editor-toolbar";
 			parent.insertBefore(this.toolbarNode,nextSibling);
-			this.domNodes.push(this.toolbarNode);
 			this.renderChildren(this.toolbarNode,null);
+			this.domNodes.push(this.toolbarNode);
 		}
 		// Create our element
 		var editInfo = this.getEditInfo(),
@@ -137,6 +141,9 @@ function editTextWidgetFactory(toolbarEngine,nonToolbarEngine) {
 		return {value: value || "", type: type, update: update};
 	};
 
+	/*
+	Handle an edit text operation message from the toolbar
+	*/
 	EditTextWidget.prototype.handleEditTextOperationMessage = function(event) {
 		// Prepare information about the operation
 		var operation = this.engine.createTextOperation();
@@ -145,13 +152,16 @@ function editTextWidgetFactory(toolbarEngine,nonToolbarEngine) {
 		if(handler) {
 			handler.call(this,event,operation);
 		}
-
+		// Execute the operation via the engine
 		var newText = this.engine.executeTextOperation(operation);
 		// Fix the tiddler height and save changes
 		this.engine.fixHeight();
 		this.saveChanges(newText);
 	};
 
+	/*
+	Compute the internal state of the widget
+	*/
 	EditTextWidget.prototype.execute = function() {
 		// Get our parameters
 		this.editTitle = this.getAttribute("tiddler",this.getVariable("currentTiddler"));
@@ -191,7 +201,7 @@ function editTextWidgetFactory(toolbarEngine,nonToolbarEngine) {
 			}
 			type = type || "text";
 		}
-
+		// Get the rest of our parameters
 		this.editTag = this.getAttribute("tag",tag) || "input";
 		this.editType = this.getAttribute("type",type);
 		// Make the child widgets
@@ -201,6 +211,9 @@ function editTextWidgetFactory(toolbarEngine,nonToolbarEngine) {
 		this.editShowToolbar = (this.editShowToolbar === "yes") && !!(this.children && this.children.length > 0) && (!this.document.isTiddlyWikiFakeDom);
 	};
 
+	/*
+	Selectively refreshes the widget if needed. Returns true if the widget or any of its children needed re-rendering
+	*/
 	EditTextWidget.prototype.refresh = function(changedTiddlers) {
 		var changedAttributes = this.computeAttributes();
 		// Completely rerender if any of our attributes have changed
@@ -221,14 +234,24 @@ function editTextWidgetFactory(toolbarEngine,nonToolbarEngine) {
 		}
 	};
 
+	/*
+	Update the editor with new text. This method is separate from updateEditorDomNode()
+	so that subclasses can override updateEditor() and still use updateEditorDomNode()
+	*/
 	EditTextWidget.prototype.updateEditor = function(text,type) {
 		this.updateEditorDomNode(text,type);
 	};
 
+	/*
+	Update the editor dom node with new text
+	*/
 	EditTextWidget.prototype.updateEditorDomNode = function(text,type) {
 		this.engine.setText(text,type);
 	};
 
+	/*
+	Save changes back to the tiddler store
+	*/
 	EditTextWidget.prototype.saveChanges = function(text) {
 		var editInfo = this.getEditInfo();
 		if(text !== editInfo.value) {
@@ -236,6 +259,9 @@ function editTextWidgetFactory(toolbarEngine,nonToolbarEngine) {
 		}
 	};
 
+	/*
+	Handle a dom "keydown" event, which we'll bubble up to our container for the keyboard widgets benefit
+	*/
 	EditTextWidget.prototype.handleKeydownEvent = function(event) {
 		// Check for a keyboard shortcut
 		if(this.toolbarNode) {
@@ -256,17 +282,20 @@ function editTextWidgetFactory(toolbarEngine,nonToolbarEngine) {
 				}
 			}
 		}
-
+		// Propogate the event to the container
 		if(this.propogateKeydownEvent(event)) {
 			// Ignore the keydown if it was already handled
 			event.preventDefault();
 			event.stopPropagation();
 			return true;
 		}
-
+		// Otherwise, process the keydown normally
 		return false;
 	};
 
+	/*
+	Propogate keydown events to our container for the keyboard widgets benefit
+	*/
 	EditTextWidget.prototype.propogateKeydownEvent = function(event) {
 		var newEvent = this.cloneEvent(event,["keyCode","code","which","key","metaKey","ctrlKey","altKey","shiftKey"]);
 		return !this.parentDomNode.dispatchEvent(newEvent);
@@ -289,12 +318,16 @@ function editTextWidgetFactory(toolbarEngine,nonToolbarEngine) {
 		return dispatchNode.dispatchEvent(newEvent);
 	};
 
+	/*
+	Propogate drag and drop events with File data to our container for the dropzone widgets benefit.
+	If there are no Files, let the browser handle it.
+	*/
 	EditTextWidget.prototype.handleDropEvent = function(event) {
 		if($tw.utils.dragEventContainsFiles(event)) {
 			event.preventDefault();
 			event.stopPropagation();
 			this.dispatchDOMEvent(this.cloneEvent(event,["dataTransfer"]));
-		}
+		} 
 	};
 
 	EditTextWidget.prototype.handlePasteEvent = function(event) {

core/modules/editor/operations/bitmap/clear.js

@@ -2,6 +2,9 @@
 title: $:/core/modules/editor/operations/bitmap/clear.js
 type: application/javascript
 module-type: bitmapeditoroperation
+
+Bitmap editor operation to clear the image
+
 \*/
 
 "use strict";

core/modules/editor/operations/bitmap/resize.js

@@ -2,6 +2,9 @@
 title: $:/core/modules/editor/operations/bitmap/resize.js
 type: application/javascript
 module-type: bitmapeditoroperation
+
+Bitmap editor operation to resize the image
+
 \*/
 
 "use strict";
@@ -14,7 +17,7 @@ exports["resize"] = function(event) {
 	if(newWidth > 0 && newHeight > 0 && !(newWidth === this.currCanvas.width && newHeight === this.currCanvas.height)) {
 		this.changeCanvasSize(newWidth,newHeight);
 	}
-
+	// Update the input controls
 	this.refreshToolbar();
 	// Save the image into the tiddler
 	this.saveChanges();

core/modules/editor/operations/bitmap/rotate-left.js

@@ -2,6 +2,9 @@
 title: $:/core/modules/editor/operations/bitmap/rotate-left.js
 type: application/javascript
 module-type: bitmapeditoroperation
+
+Bitmap editor operation to rotate the image left by 90 degrees
+
 \*/
 
 "use strict";

core/modules/editor/operations/text/excise.js

@@ -2,6 +2,9 @@
 title: $:/core/modules/editor/operations/text/excise.js
 type: application/javascript
 module-type: texteditoroperation
+
+Text editor operation to excise the selection to a new tiddler
+
 \*/
 
 "use strict";

core/modules/editor/operations/text/insert-text.js

@@ -2,6 +2,9 @@
 title: $:/core/modules/editor/operations/text/insert-text.js
 type: application/javascript
 module-type: texteditoroperation
+
+Text editor operation insert text at the caret position. If there is a selection it is replaced.
+
 \*/
 
 "use strict";

core/modules/editor/operations/text/make-link.js

@@ -2,6 +2,9 @@
 title: $:/core/modules/editor/operations/text/make-link.js
 type: application/javascript
 module-type: texteditoroperation
+
+Text editor operation to make a link
+
 \*/
 
 "use strict";

core/modules/editor/operations/text/prefix-lines.js

@@ -2,6 +2,9 @@
 title: $:/core/modules/editor/operations/text/prefix-lines.js
 type: application/javascript
 module-type: texteditoroperation
+
+Text editor operation to add a prefix to the selected lines
+
 \*/
 
 "use strict";
@@ -23,16 +26,16 @@ exports["prefix-lines"] = function(event,operation) {
 			line = line.substring(event.paramObject.character.length);
 			count++;
 		}
-
+		// Remove any whitespace
 		while(line.charAt(0) === " ") {
 			line = line.substring(1);
 		}
-
+		// We're done if we removed the exact required prefix, otherwise add it
 		if(count !== targetCount) {
 			// Apply the prefix
 			line =  prefix + " " + line;
 		}
-
+		// Save the modified line
 		lines[index] = line;
 	});
 	// Stitch the replacement text together and set the selection

core/modules/editor/operations/text/replace-all.js

@@ -2,6 +2,9 @@
 title: $:/core/modules/editor/operations/text/replace-all.js
 type: application/javascript
 module-type: texteditoroperation
+
+Text editor operation to replace the entire text
+
 \*/
 
 "use strict";

core/modules/editor/operations/text/replace-selection.js

@@ -2,6 +2,9 @@
 title: $:/core/modules/editor/operations/text/replace-selection.js
 type: application/javascript
 module-type: texteditoroperation
+
+Text editor operation to replace the selection
+
 \*/
 
 "use strict";

core/modules/editor/operations/text/save-selection.js

@@ -2,6 +2,9 @@
 title: $:/core/modules/editor/operations/text/save-selection.js
 type: application/javascript
 module-type: texteditoroperation
+
+Text editor operation to save the current selection in a specified tiddler
+
 \*/
 
 "use strict";

core/modules/editor/operations/text/wrap-lines.js

@@ -2,6 +2,9 @@
 title: $:/core/modules/editor/operations/text/wrap-lines.js
 type: application/javascript
 module-type: texteditoroperation
+
+Text editor operation to wrap the selected lines with a prefix and suffix
+
 \*/
 
 "use strict";
@@ -12,14 +15,14 @@ exports["wrap-lines"] = function(event,operation) {
 	if($tw.utils.endsWith(operation.text.substring(0,operation.selStart), prefix + "\n") &&
 			$tw.utils.startsWith(operation.text.substring(operation.selEnd), "\n" + suffix)) {
 		// Selected text is already surrounded by prefix and suffix: Remove them
-
+		// Cut selected text plus prefix and suffix
 		operation.cutStart = operation.selStart - (prefix.length + 1);
 		operation.cutEnd = operation.selEnd + suffix.length + 1;
 		// Also cut the following newline (if there is any)
 		if (operation.text[operation.cutEnd] === "\n") {
 			operation.cutEnd++;
 		}
-
+		// Replace with selection
 		operation.replacement = operation.text.substring(operation.selStart,operation.selEnd);
 		// Select text that was in between prefix and suffix
 		operation.newSelStart = operation.cutStart;

core/modules/editor/operations/text/wrap-selection.js

@@ -2,6 +2,9 @@
 title: $:/core/modules/editor/operations/text/wrap-selection.js
 type: application/javascript
 module-type: texteditoroperation
+
+Text editor operation to wrap the selection with the specified prefix and suffix
+
 \*/
 
 "use strict";
@@ -14,11 +17,11 @@ exports["wrap-selection"] = function(event,operation) {
 		selLength = o.selEnd - o.selStart;
 
 	// This function detects, if trailing spaces are part of the selection __and__ if the user wants to handle them
-
+	// Returns "yes", "start", "end", "no" (default)
 	//	yes .. there are trailing spaces at both ends
-
+	//	start .. there are trailing spaces at the start
 	//	end .. there are trailing spaces at the end
-
+	//	no .. no trailing spaces are taken into account
 	var trailingSpaceAt = function(sel) {
 		var _start,
 			_end,
@@ -61,6 +64,7 @@ exports["wrap-selection"] = function(event,operation) {
 		}
 	}
 
+	// options: lenPrefix, lenSuffix
 	function removePrefixSuffix(options) {
 		options = options || {};
 		var _lenPrefix = options.lenPrefix || 0;

core/modules/filter-tracker.js

@@ -1,95 +0,0 @@
-/*\
-title: $:/core/modules/filter-tracker.js
-type: application/javascript
-module-type: global
-\*/
-
-"use strict";
-
-class FilterTracker {
-	constructor(wiki) {
-		this.wiki = wiki;
-		this.trackers = new Map();
-		this.nextTrackerId = 1;
-	}
-
-	handleChangeEvent(changes) {
-		this.processTrackers();
-		this.processChanges(changes);
-	}
-
-	track(options = {}) {
-		const {
-			filterString,
-			fnEnter,
-			fnLeave,
-			fnChange,
-			fnProcess
-		} = options;
-		const id = this.nextTrackerId++;
-		const tracker = {
-			id,
-			filterString,
-			fnEnter,
-			fnLeave,
-			fnChange,
-			fnProcess,
-			previousResults: [],
-			resultValues: {}
-		};
-		this.trackers.set(id, tracker);
-		// Process the tracker
-		this.processTracker(id);
-		return id;
-	}
-
-	untrack(id) {
-		this.trackers.delete(id);
-	}
-
-	processTrackers() {
-		for(const id of this.trackers.keys()) {
-			this.processTracker(id);
-		}
-	}
-
-	processTracker(id) {
-		const tracker = this.trackers.get(id);
-		if(!tracker) return;
-		const results = [];
-		// Evaluate the filter and remove duplicate results
-		$tw.utils.each(this.wiki.filterTiddlers(tracker.filterString), title => {
-			$tw.utils.pushTop(results, title);
-		});
-		// Process the newly entered results
-		results.forEach(title => {
-			if(!tracker.previousResults.includes(title) && !tracker.resultValues[title] && tracker.fnEnter) {
-				tracker.resultValues[title] = tracker.fnEnter(title) || true;
-			}
-		});
-		// Process the results that have just left
-		tracker.previousResults.forEach(title => {
-			if(!results.includes(title) && tracker.resultValues[title] && tracker.fnLeave) {
-				tracker.fnLeave(title, tracker.resultValues[title]);
-				delete tracker.resultValues[title];
-			}
-		});
-		// Update the previous results
-		tracker.previousResults = results;
-	}
-
-	processChanges(changes) {
-		for(const tracker of this.trackers.values()) {
-			Object.keys(changes).forEach(title => {
-				if(title && tracker.previousResults.includes(title) && tracker.fnChange) {
-					tracker.resultValues[title] = tracker.fnChange(title, tracker.resultValues[title]) || tracker.resultValues[title];
-				}
-			});
-			if(tracker.fnProcess) {
-				tracker.fnProcess(changes);
-			}
-		}
-	}
-}
-
-exports.FilterTracker = FilterTracker;

core/modules/filterrunprefixes/all.js

@@ -2,10 +2,17 @@
 title: $:/core/modules/filterrunprefixes/all.js
 type: application/javascript
 module-type: filterrunprefix
+
+Union of sets without de-duplication.
+Equivalent to = filter run prefix.
+
 \*/
 
 "use strict";
 
+/*
+Export our filter prefix function
+*/
 exports.all = function(operationSubFunction) {
 	return function(results,source,widget) {
 		results.push.apply(results, operationSubFunction(source,widget));

core/modules/filterrunprefixes/and.js

@@ -2,10 +2,17 @@
 title: $:/core/modules/filterrunprefixes/and.js
 type: application/javascript
 module-type: filterrunprefix
+
+Intersection of sets.
+Equivalent to + filter run prefix.
+
 \*/
 
 "use strict";
 
+/*
+Export our filter prefix function
+*/
 exports.and = function(operationSubFunction,options) {
 	return function(results,source,widget) {
 		// This replaces all the elements of the array, but keeps the actual array so that references to it are preserved

core/modules/filterrunprefixes/cascade.js

@@ -6,6 +6,9 @@ module-type: filterrunprefix
 
 "use strict";
 
+/*
+Export our filter prefix function
+*/
 exports.cascade = function(operationSubFunction,options) {
 	return function(results,source,widget) {
 		if(results.length !== 0) {
@@ -21,7 +24,7 @@ exports.cascade = function(operationSubFunction,options) {
 					}
 					var output = filterFnList[index](options.wiki.makeTiddlerIterator([title]),widget.makeFakeWidgetWithVariables({
 						"currentTiddler": "" + title,
-						"..currentTiddler": widget.getVariable("currentTiddler",{defaultValue:""})
+						"..currentTiddler": widget.getVariable("currentTiddler","")
 					}));
 					if(output.length !== 0) {
 						result = output[0];

core/modules/filterrunprefixes/else.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filterrunprefixes/else.js
 type: application/javascript
 module-type: filterrunprefix
+
+Equivalent to ~ filter run prefix.
+
 \*/
 
 "use strict";
 
+/*
+Export our filter prefix function
+*/
 exports.else = function(operationSubFunction) {
 	return function(results,source,widget) {
 		if(results.length === 0) {

core/modules/filterrunprefixes/except.js

@@ -2,10 +2,17 @@
 title: $:/core/modules/filterrunprefixes/except.js
 type: application/javascript
 module-type: filterrunprefix
+
+Difference of sets.
+Equivalent to - filter run prefix.
+
 \*/
 
 "use strict";
 
+/*
+Export our filter prefix function
+*/
 exports.except = function(operationSubFunction) {
 	return function(results,source,widget) {
 		results.remove(operationSubFunction(source,widget));

core/modules/filterrunprefixes/filter.js

@@ -2,10 +2,14 @@
 title: $:/core/modules/filterrunprefixes/filter.js
 type: application/javascript
 module-type: filterrunprefix
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.filter = function(operationSubFunction,options) {
 	return function(results,source,widget) {
 		if(results.length > 0) {
@@ -14,7 +18,7 @@ exports.filter = function(operationSubFunction,options) {
 			results.each(function(title) {
 				var filtered = operationSubFunction(options.wiki.makeTiddlerIterator([title]),widget.makeFakeWidgetWithVariables({
 					"currentTiddler": "" + title,
-					"..currentTiddler": widget.getVariable("currentTiddler",{defaultValue:""}),
+					"..currentTiddler": widget.getVariable("currentTiddler",""),
 					"index": "" + index,
 					"revIndex": "" +  (results.length - 1 - index),
 					"length": "" + results.length

core/modules/filterrunprefixes/intersection.js

@@ -2,10 +2,14 @@
 title: $:/core/modules/filterrunprefixes/intersection.js
 type: application/javascript
 module-type: filterrunprefix
+
 \*/
 
 "use strict";
 
+/*
+Export our filter prefix function
+*/
 exports.intersection = function(operationSubFunction) {
 	return function(results,source,widget) {
 		if(results.length !== 0) {

core/modules/filterrunprefixes/let.js

@@ -2,10 +2,18 @@
 title: $:/core/modules/filterrunprefixes/let.js
 type: application/javascript
 module-type: filterrunprefix
+
+Assign a value to a variable
+
 \*/
 
+/*jslint node: true, browser: true */
+/*global $tw: false */
 "use strict";
 
+/*
+Export our filter prefix function
+*/
 exports.let = function(operationSubFunction,options) {
 	// Return the filter run prefix function
 	return function(results,source,widget) {
@@ -22,7 +30,7 @@ exports.let = function(operationSubFunction,options) {
 		if(typeof name !== "string" || name.length === 0) {
 			return;
 		}
-
+		// Assign the result of the subfunction to the variable
 		var variables = {};
 		variables[name] = resultList;
 		// Return the variables

core/modules/filterrunprefixes/map.js

@@ -6,6 +6,9 @@ module-type: filterrunprefix
 
 "use strict";
 
+/*
+Export our filter prefix function
+*/
 exports.map = function(operationSubFunction,options) {
 	return function(results,source,widget) {
 		if(results.length > 0) {
@@ -17,7 +20,7 @@ exports.map = function(operationSubFunction,options) {
 			$tw.utils.each(inputTitles,function(title) {
 				var filtered = operationSubFunction(options.wiki.makeTiddlerIterator([title]),widget.makeFakeWidgetWithVariables({
 					"currentTiddler": "" + title,
-					"..currentTiddler": widget.getVariable("currentTiddler",{defaultValue:""}),
+					"..currentTiddler": widget.getVariable("currentTiddler",""),
 					"index": "" + index,
 					"revIndex": "" +  (inputTitles.length - 1 - index),
 					"length": "" + inputTitles.length

core/modules/filterrunprefixes/or.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filterrunprefixes/or.js
 type: application/javascript
 module-type: filterrunprefix
+
+Equivalent to a filter run with no prefix.
+
 \*/
 
 "use strict";
 
+/*
+Export our filter prefix function
+*/
 exports.or = function(operationSubFunction) {
 	return function(results,source,widget) {
 		results.pushTop(operationSubFunction(source,widget));

core/modules/filterrunprefixes/reduce.js

@@ -6,6 +6,9 @@ module-type: filterrunprefix
 
 "use strict";
 
+/*
+Export our filter prefix function
+*/
 exports.reduce = function(operationSubFunction,options) {
 	return function(results,source,widget) {
 		if(results.length > 0) {
@@ -14,7 +17,7 @@ exports.reduce = function(operationSubFunction,options) {
 			results.each(function(title) {
 				var list = operationSubFunction(options.wiki.makeTiddlerIterator([title]),widget.makeFakeWidgetWithVariables({
 					"currentTiddler": "" + title,
-					"..currentTiddler": widget.getVariable("currentTiddler",{defaultValue:""}),
+					"..currentTiddler": widget.getVariable("currentTiddler"),
 					"index": "" + index,
 					"revIndex": "" +  (results.length - 1 - index),
 					"length": "" + results.length,

core/modules/filterrunprefixes/sort.js

@@ -2,10 +2,14 @@
 title: $:/core/modules/filterrunprefixes/sort.js
 type: application/javascript
 module-type: filterrunprefix
+
 \*/
 
 "use strict";
 
+/*
+Export our filter prefix function
+*/
 exports.sort = function(operationSubFunction,options) {
 	return function(results,source,widget) {
 		if(results.length > 0) {
@@ -20,7 +24,7 @@ exports.sort = function(operationSubFunction,options) {
 			results.each(function(title) {
 				var key = operationSubFunction(options.wiki.makeTiddlerIterator([title]),widget.makeFakeWidgetWithVariables({
 					"currentTiddler": "" + title,
-					"..currentTiddler": widget.getVariable("currentTiddler",{defaultValue:""})
+					"..currentTiddler": widget.getVariable("currentTiddler")
 				}));
 				sortKeys.push(key[0] || "");
 			});
@@ -29,7 +33,7 @@ exports.sort = function(operationSubFunction,options) {
 			for(var t=0; t<inputTitles.length; t++) {
 				indexes[t] = t;
 			}
-
+			// Sort the indexes
 			compareFn = $tw.utils.makeCompareFunction(sortType,{defaultType: "string", invert:invert, isCaseSensitive:isCaseSensitive});
 			indexes = indexes.sort(function(a,b) {
 					return compareFn(sortKeys[a],sortKeys[b]);

core/modules/filterrunprefixes/then.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filterrunprefixes/then.js
 type: application/javascript
 module-type: filterrunprefix
+
+Replace results of previous runs unless empty
+
 \*/
 
 "use strict";
 
+/*
+Export our filter prefix function
+*/
 exports.then = function(operationSubFunction) {
 	return function(results,source,widget) {
 		if(results.length !== 0) {

core/modules/filters.js

@@ -2,28 +2,39 @@
 title: $:/core/modules/filters.js
 type: application/javascript
 module-type: wikimethod
+
+Adds tiddler filtering methods to the $tw.Wiki object.
+
 \*/
 
 "use strict";
 
 var widgetClass = require("$:/core/modules/widgets/widget.js").widget;
 
+/* Maximum permitted filter recursion depth */
 var MAX_FILTER_DEPTH = 300;
 
+/*
+Parses an operation (i.e. a run) within a filter string
+	operators: Array of array of operator nodes into which results should be inserted
+	filterString: filter string
+	p: start position within the string
+Returns the new start position, after the parsed operation
+*/
 function parseFilterOperation(operators,filterString,p) {
 	var nextBracketPos, operator;
 	// Skip the starting square bracket
 	if(filterString.charAt(p++) !== "[") {
 		throw "Missing [ in filter expression";
 	}
-
+	// Process each operator in turn
 	do {
 		operator = {};
 		// Check for an operator prefix
 		if(filterString.charAt(p) === "!") {
 			operator.prefix = filterString.charAt(p++);
 		}
-
+		// Get the operator name
 		nextBracketPos = filterString.substring(p).search(/[\[\{<\/\(]/);
 		if(nextBracketPos === -1) {
 			throw "Missing [ in filter expression";
@@ -44,12 +55,12 @@ function parseFilterOperation(operators,filterString,p) {
 				$tw.utils.each(subsuffix.split(","),function(entry) {
 					entry = $tw.utils.trim(entry);
 					if(entry) {
-						operator.suffixes[operator.suffixes.length - 1].push(entry);
+						operator.suffixes[operator.suffixes.length - 1].push(entry); 
 					}
 				});
 			});
 		}
-
+		// Empty operator means: title
 		else if(operator.operator === "") {
 			operator.operator = "title";
 		}
@@ -77,8 +88,8 @@ function parseFilterOperation(operators,filterString,p) {
 						rexMatch = rex.exec(filterString.substring(p));
 					if(rexMatch) {
 						operator.regexp = new RegExp(rexMatch[1], rexMatch[2]);
-	// DEPRECATION WARNING
+						// DEPRECATION WARNING
-	console.log("WARNING: Filter",operator.operator,"has a deprecated regexp operand",operator.regexp);
+						console.log("WARNING: Filter",operator.operator,"has a deprecated regexp operand",operator.regexp);
 						nextBracketPos = p + rex.lastIndex - 1;
 					}
 					else {
@@ -114,16 +125,20 @@ function parseFilterOperation(operators,filterString,p) {
 			}
 		}
 
+		// Push this operator
 		operators.push(operator);
 	} while(filterString.charAt(p) !== "]");
 	// Skip the ending square bracket
 	if(filterString.charAt(p++) !== "]") {
 		throw "Missing ] in filter expression";
 	}
-
+	// Return the parsing position
 	return p;
 }
 
+/*
+Parse a filter string
+*/
 exports.parseFilter = function(filterString) {
 	filterString = filterString || "";
 	var results = [], // Array of arrays of operator nodes {operator:,operand:}
@@ -132,11 +147,11 @@ exports.parseFilter = function(filterString) {
 	var whitespaceRegExp = /(\s+)/mg,
 		// Groups:
 		// 1 - entire filter run prefix
-
+		// 2 - filter run prefix itself
 		// 3 - filter run prefix suffixes
-
+		// 4 - opening square bracket following filter run prefix
 		// 5 - double quoted string following filter run prefix
-
+		// 6 - single quoted string following filter run prefix
 		// 7 - anything except for whitespace and square brackets
 		operandRegExp = /((?:\+|\-|~|(?:=>?)|\:(\w+)(?:\:([\w\:, ]*))?)?)(?:(\[)|(?:"([^"]*)")|(?:'([^']*)')|([^\s\[\]]+))/mg;
 	while(p < filterString.length) {
@@ -146,7 +161,7 @@ exports.parseFilter = function(filterString) {
 		if(match && match.index === p) {
 			p = p + match[0].length;
 		}
-
+		// Match the start of the operation
 		if(p < filterString.length) {
 			operandRegExp.lastIndex = p;
 			var operation = {
@@ -163,7 +178,7 @@ exports.parseFilter = function(filterString) {
 					if(match[2]) {
 						operation.namedPrefix = match[2];
 					}
-
+					// Suffixes for filter run prefix
 					if(match[3]) {
 						operation.suffixes = [];
 						$tw.utils.each(match[3].split(":"),function(subsuffix) {
@@ -177,7 +192,7 @@ exports.parseFilter = function(filterString) {
 						});
 					}
 				}
-
+				// Opening square bracket
 				if(match[4]) {
 					p = parseFilterOperation(operation.operators,filterString,p);
 				} else {
@@ -187,7 +202,7 @@ exports.parseFilter = function(filterString) {
 				// No filter run prefix
 				p = parseFilterOperation(operation.operators,filterString,p);
 			}
-
+			// Quoted strings and unquoted title
 			if(match[5] || match[6] || match[7]) { // Double quoted string, single quoted string or unquoted title
 				operation.operators.push(
 					{operator: "title", operands: [{text: match[5] || match[6] || match[7]}]}
@@ -217,9 +232,19 @@ exports.getFilterRunPrefixes = function() {
 
 exports.filterTiddlers = function(filterString,widget,source) {
 	var fn = this.compileFilter(filterString);
-	return fn.call(this,source,widget);
+	try {
+		const fnResult = fn.call(this,source,widget);
+		return fnResult;
+	} catch(e) {
+		return [`${$tw.language.getString("Error/Filter")}: ${e}`];
+	}
 };
 
+/*
+Compile a filter into a function with the signature fn(source,widget) where:
+source: an iterator function for the source tiddlers, called source(iterator), where iterator is called as iterator(tiddler,title)
+widget: an optional widget node for retrieving the current tiddler etc.
+*/
 exports.compileFilter = function(filterString) {
 	if(!this.filterCache) {
 		this.filterCache = Object.create(null);
@@ -237,7 +262,7 @@ exports.compileFilter = function(filterString) {
 			return [$tw.language.getString("Error/Filter") + ": " + e];
 		};
 	}
-
+	// Get the hashmap of filter operator functions
 	var filterOperators = this.getFilterOperators();
 	// Assemble array of functions, one for each operation
 	var operationFunctions = [];
@@ -282,7 +307,7 @@ exports.compileFilter = function(filterString) {
 							operand.value = "";
 							operand.multiValue = [];
 						}
-						operand.isMultiValueOperand = true;
+						operand.isMultiValueOperand = true;	
 					} else {
 						operand.value = operand.text;
 						operand.multiValue = [operand.value];
@@ -294,19 +319,19 @@ exports.compileFilter = function(filterString) {
 
 				// Invoke the appropriate filteroperator module
 				results = operatorFunction(accumulator,{
-							operator: operator.operator,
+					operator: operator.operator,
-							operand: operands.length > 0 ? operands[0] : undefined,
+					operand: operands.length > 0 ? operands[0] : undefined,
-							operands: operands,
+					operands: operands,
-							multiValueOperands: multiValueOperands,
+					multiValueOperands: multiValueOperands,
-							isMultiValueOperand: isMultiValueOperand,
+					isMultiValueOperand: isMultiValueOperand,
-							prefix: operator.prefix,
+					prefix: operator.prefix,
-							suffix: operator.suffix,
+					suffix: operator.suffix,
-							suffixes: operator.suffixes,
+					suffixes: operator.suffixes,
-							regexp: operator.regexp
+					regexp: operator.regexp
-						},{
+				},{
-							wiki: self,
+					wiki: self,
-							widget: widget
+					widget: widget
-						});
+				});
 				if($tw.utils.isArray(results)) {
 					accumulator = self.makeTiddlerIterator(results);
 				} else {
@@ -340,7 +365,7 @@ exports.compileFilter = function(filterString) {
 					return filterRunPrefixes["else"](operationSubFunction, options);
 				case "=>": // This operation is applied to the main results so far, and the results are assigned to a variable
 					return filterRunPrefixes["let"](operationSubFunction, options);
-				default:
+				default: 
 					if(operation.namedPrefix && filterRunPrefixes[operation.namedPrefix]) {
 						return filterRunPrefixes[operation.namedPrefix](operationSubFunction, options);
 					} else {
@@ -382,7 +407,7 @@ exports.compileFilter = function(filterString) {
 	});
 	if(this.filterCacheCount >= 2000) {
 		// To prevent memory leak, we maintain an upper limit for cache size.
-
+		// Reset if exceeded. This should give us 95% of the benefit
 		// that no cache limit would give us.
 		this.filterCache = Object.create(null);
 		this.filterCacheCount = 0;

core/modules/filters/addprefix.js

@@ -2,10 +2,18 @@
 title: $:/core/modules/filters/addprefix.js
 type: application/javascript
 module-type: filteroperator
+
+Filter operator for adding a prefix to each title in the list. This is
+especially useful in contexts where only a filter expression is allowed
+and macro substitution isn't available.
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.addprefix = function(source,operator,options) {
 	var results = [];
 	source(function(tiddler,title) {

core/modules/filters/addsuffix.js

@@ -2,10 +2,18 @@
 title: $:/core/modules/filters/addsuffix.js
 type: application/javascript
 module-type: filteroperator
+
+Filter operator for adding a suffix to each title in the list. This is
+especially useful in contexts where only a filter expression is allowed
+and macro substitution isn't available.
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.addsuffix = function(source,operator,options) {
 	var results = [];
 	source(function(tiddler,title) {

core/modules/filters/after.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/after.js
 type: application/javascript
 module-type: filteroperator
+
+Filter operator returning the tiddler from the current list that is after the tiddler named in the operand.
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.after = function(source,operator,options) {
 	var results = [];
 	source(function(tiddler,title) {

core/modules/filters/all.js

@@ -2,6 +2,11 @@
 title: $:/core/modules/filters/all.js
 type: application/javascript
 module-type: filteroperator
+
+Filter operator for selecting tiddlers
+
+[all[shadows+tiddlers]]
+
 \*/
 
 "use strict";
@@ -16,6 +21,9 @@ function getAllFilterOperators() {
 	return allFilterOperators;
 }
 
+/*
+Export our filter function
+*/
 exports.all = function(source,operator,options) {
 	// Check for common optimisations
 	var subops = operator.operand.split("+");
@@ -30,7 +38,7 @@ exports.all = function(source,operator,options) {
 	} else if(subops.length === 2 && subops[0] === "shadows" && subops[1] === "tiddlers") {
 		return options.wiki.eachShadowPlusTiddlers;
 	}
-
+	// Do it the hard way
 	// Get our suboperators
 	var allFilterOperators = getAllFilterOperators();
 	// Cycle through the suboperators accumulating their results

core/modules/filters/all/current.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/all/current.js
 type: application/javascript
 module-type: allfilteroperator
+
+Filter function for [all[current]]
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.current = function(source,prefix,options) {
 	var currTiddlerTitle = options.widget && options.widget.getVariable("currentTiddler");
 	if(currTiddlerTitle) {

core/modules/filters/all/missing.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/all/missing.js
 type: application/javascript
 module-type: allfilteroperator
+
+Filter function for [all[missing]]
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.missing = function(source,prefix,options) {
 	return options.wiki.getMissingTitles();
 };

core/modules/filters/all/orphans.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/all/orphans.js
 type: application/javascript
 module-type: allfilteroperator
+
+Filter function for [all[orphans]]
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.orphans = function(source,prefix,options) {
 	return options.wiki.getOrphanTitles();
 };

core/modules/filters/all/shadows.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/all/shadows.js
 type: application/javascript
 module-type: allfilteroperator
+
+Filter function for [all[shadows]]
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.shadows = function(source,prefix,options) {
 	return options.wiki.allShadowTitles();
 };

core/modules/filters/all/tags.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/all/tags.js
 type: application/javascript
 module-type: allfilteroperator
+
+Filter function for [all[tags]]
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.tags = function(source,prefix,options) {
 	return Object.keys(options.wiki.getTagMap());
 };

core/modules/filters/all/tiddlers.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/all/tiddlers.js
 type: application/javascript
 module-type: allfilteroperator
+
+Filter function for [all[tiddlers]]
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.tiddlers = function(source,prefix,options) {
 	return options.wiki.allTitles();
 };

core/modules/filters/backlinks.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/backlinks.js
 type: application/javascript
 module-type: filteroperator
+
+Filter operator for returning all the backlinks from a tiddler
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.backlinks = function(source,operator,options) {
 	var results = new $tw.utils.LinkedList();
 	source(function(tiddler,title) {

core/modules/filters/backtranscludes.js

@@ -2,9 +2,15 @@
 title: $:/core/modules/filters/backtranscludes.js
 type: application/javascript
 module-type: filteroperator
+
+Filter operator for returning all the backtranscludes from a tiddler
+
 \*/
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.backtranscludes = function(source,operator,options) {
 	var results = new $tw.utils.LinkedList();
 	source(function(tiddler,title) {

core/modules/filters/before.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/before.js
 type: application/javascript
 module-type: filteroperator
+
+Filter operator returning the tiddler from the current list that is before the tiddler named in the operand.
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.before = function(source,operator,options) {
 	var results = [];
 	source(function(tiddler,title) {

core/modules/filters/commands.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/commands.js
 type: application/javascript
 module-type: filteroperator
+
+Filter operator for returning the names of the commands available in this wiki
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.commands = function(source,operator,options) {
 	var results = [];
 	$tw.utils.each($tw.commands,function(commandInfo,name) {

core/modules/filters/compare.js

@@ -2,6 +2,9 @@
 title: $:/core/modules/filters/compare.js
 type: application/javascript
 module-type: filteroperator
+
+General purpose comparison operator
+
 \*/
 
 "use strict";

core/modules/filters/contains.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/contains.js
 type: application/javascript
 module-type: filteroperator
+
+Filter operator for finding values in array fields
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.contains = function(source,operator,options) {
 	var results = [],
 		fieldname = operator.suffix || "list";

core/modules/filters/count.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/count.js
 type: application/javascript
 module-type: filteroperator
+
+Filter operator returning the number of entries in the current list.
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.count = function(source,operator,options) {
 	var count = 0;
 	source(function(tiddler,title) {

core/modules/filters/crypto.js

@@ -2,6 +2,9 @@
 title: $:/core/modules/filters/crypto.js
 type: application/javascript
 module-type: filteroperator
+
+Filter operators for cryptography, using the Stanford JavaScript library
+
 \*/
 
 "use strict";

core/modules/filters/days.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/days.js
 type: application/javascript
 module-type: filteroperator
+
+Filter operator that selects tiddlers with a specified date field within a specified date interval.
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.days = function(source,operator,options) {
 	var results = [],
 		fieldName = operator.suffix || "modified",

core/modules/filters/deserializers.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/deserializers.js
 type: application/javascript
 module-type: filteroperator
+
+Filter operator for returning the names of the deserializers in this wiki
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.deserializers = function(source,operator,options) {
 	var results = [];
 	$tw.utils.each($tw.Wiki.tiddlerDeserializerModules,function(deserializer,type) {

core/modules/filters/duplicateslugs.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/duplicateslugs.js
 type: application/javascript
 module-type: filteroperator
+
+Filter function for [duplicateslugs[]]
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.duplicateslugs = function(source,operator,options) {
 	var slugs = Object.create(null), // Hashmap by slug of title, replaced with "true" if the duplicate title has already been output
 		results = [];

core/modules/filters/each.js

@@ -2,10 +2,17 @@
 title: $:/core/modules/filters/each.js
 type: application/javascript
 module-type: filteroperator
+
+Filter operator that selects one tiddler for each unique value of the specified field.
+With suffix "list", selects all tiddlers that are values in a specified list field.
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.each = function(source,operator,options) {
 	var results =[] ,
 	value,values = {},

core/modules/filters/eachday.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/eachday.js
 type: application/javascript
 module-type: filteroperator
+
+Filter operator that selects one tiddler for each unique day covered by the specified date field
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.eachday = function(source,operator,options) {
 	var results = [],
 		values = [],

core/modules/filters/editiondescription.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/editiondescription.js
 type: application/javascript
 module-type: filteroperator
+
+Filter operator for returning the descriptions of the specified edition names
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.editiondescription = function(source,operator,options) {
 	var results = [];
 	if($tw.node) {

core/modules/filters/editions.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/editions.js
 type: application/javascript
 module-type: filteroperator
+
+Filter operator for returning the names of the available editions in this wiki
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.editions = function(source,operator,options) {
 	var results = [];
 	if($tw.node) {

core/modules/filters/else.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/else.js
 type: application/javascript
 module-type: filteroperator
+
+Filter operator for replacing an empty input list with a constant, passing a non-empty input list straight through
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.else = function(source,operator,options) {
 	var results = [];
 	source(function(tiddler,title) {

core/modules/filters/encodings.js

@@ -2,10 +2,17 @@
 title: $:/core/modules/filters/decodeuricomponent.js
 type: application/javascript
 module-type: filteroperator
+
+Filter operator for applying decodeURIComponent() to each item.
+
 \*/
 
 "use strict";
 
+/*
+Export our filter functions
+*/
+
 exports.decodebase64 = function(source,operator,options) {
 	var results = [];
 	var binary = operator.suffixes && operator.suffixes[0].indexOf("binary") !== -1;

core/modules/filters/enlist.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/enlist.js
 type: application/javascript
 module-type: filteroperator
+
+Filter operator returning its operand parsed as a list
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.enlist = function(source,operator,options) {
 	var allowDuplicates = false;
 	switch(operator.suffix) {

core/modules/filters/field.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/field.js
 type: application/javascript
 module-type: filteroperator
+
+Filter operator for comparing fields for equality
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.field = function(source,operator,options) {
 	var results = [],indexedResults,
 		fieldname = operator.suffix || operator.operator || "title";

core/modules/filters/fields.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/fields.js
 type: application/javascript
 module-type: filteroperator
+
+Filter operator for returning the names of the fields on the selected tiddlers
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.fields = function(source,operator,options) {
 	var results = [],
 		fieldName,
@@ -22,13 +28,13 @@ exports.fields = function(source,operator,options) {
 				for(fieldName in tiddler.fields) {
 					(operand.indexOf(fieldName) !== -1) ? "" : $tw.utils.pushTop(results,fieldName);
 				}
-			}
+			} // else if
 			else {
 				for(fieldName in tiddler.fields) {
 					$tw.utils.pushTop(results,fieldName);
 				}
-			}
+			} // else
-		}
+		} // if (tiddler)
 	});
 	return results;
 };

core/modules/filters/filter.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/filter.js
 type: application/javascript
 module-type: filteroperator
+
+Filter operator returning those input titles that pass a subfilter
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.filter = function(source,operator,options) {
 	var filterFn = options.wiki.compileFilter(operator.operand),
 		results = [],
@@ -13,7 +19,7 @@ exports.filter = function(source,operator,options) {
 	source(function(tiddler,title) {
 		var list = filterFn.call(options.wiki,options.wiki.makeTiddlerIterator([title]),options.widget.makeFakeWidgetWithVariables({
 			"currentTiddler": "" + title,
-			"..currentTiddler": options.widget.getVariable("currentTiddler",{defaultValue:""})
+			"..currentTiddler": options.widget.getVariable("currentTiddler","")
 		}));
 		if((list.length > 0) === target) {
 			results.push(title);

core/modules/filters/format.js

@@ -17,6 +17,9 @@ function getFormatFilterOperators() {
 	return formatFilterOperators;
 }
 
+/*
+Export our filter function
+*/
 exports.format = function(source,operator,options) {
 	// Dispatch to the correct formatfilteroperator
 	var formatFilterOperators = getFormatFilterOperators();

core/modules/filters/format/date.js

@@ -6,6 +6,9 @@ module-type: formatfilteroperator
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.date = function(source,operand,options) {
 	var results = [];
 	source(function(tiddler,title) {

core/modules/filters/format/json.js

@@ -6,6 +6,9 @@ module-type: formatfilteroperator
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.json = function(source,operand,options) {
 	var results = [],
 		spaces = null;

core/modules/filters/format/relativedate.js

@@ -6,6 +6,9 @@ module-type: formatfilteroperator
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.relativedate = function(source,operand,options) {
 	var results = [];
 	source(function(tiddler,title) {

core/modules/filters/format/timestamp.js

@@ -6,6 +6,9 @@ module-type: formatfilteroperator
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.timestamp = function(source,operand,options) {
 	var results = [];
 	source(function(tiddler,title) {

core/modules/filters/format/titlelist.js

@@ -6,6 +6,9 @@ module-type: formatfilteroperator
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.titlelist = function(source,operand,options) {
 	var results = [];
 	source(function(tiddler,title) {

core/modules/filters/function.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/function.js
 type: application/javascript
 module-type: filteroperator
+
+Filter operator returning those input titles that are returned from a function
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.function = function(source,operator,options) {
 	var functionName = operator.operands[0],
 		params = [],
@@ -18,13 +24,13 @@ exports.function = function(source,operator,options) {
 	if(variableInfo && variableInfo.srcVariable && variableInfo.srcVariable.isFunctionDefinition) {
 		results = variableInfo.resultList ? variableInfo.resultList : [variableInfo.text];
 	}
-
+	// Return the input list if the function wasn't found
 	if(!results) {
 		results = [];
 		source(function(tiddler,title) {
 			results.push(title);
-		});
+		});	
 	}
-
+	// console.log(`function ${functionName} with params ${JSON.stringify(params)} results: ${JSON.stringify(results)}`);
 	return results;
 };

core/modules/filters/get.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/get.js
 type: application/javascript
 module-type: filteroperator
+
+Filter operator for replacing tiddler titles by the value of the field specified in the operand.
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.get = function(source,operator,options) {
 	var results = [];
 	source(function(tiddler,title) {

core/modules/filters/getindex.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/getindex.js
 type: application/javascript
 module-type: filteroperator
+
+returns the value at a given index of datatiddlers
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.getindex = function(source,operator,options) {
 	var data,title,results = [];
 	if(operator.operand){

core/modules/filters/getvariable.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/getvariable.js
 type: application/javascript
 module-type: filteroperator
+
+Filter operator for replacing input values by the value of the variable with the same name, or blank if the variable is missing
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.getvariable = function(source,operator,options) {
 	var results = [];
 	source(function(tiddler,title) {

core/modules/filters/has.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/has.js
 type: application/javascript
 module-type: filteroperator
+
+Filter operator for checking if a tiddler has the specified field or index
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.has = function(source,operator,options) {
 	var results = [],
 		invert = operator.prefix === "!";

core/modules/filters/haschanged.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/haschanged.js
 type: application/javascript
 module-type: filteroperator
+
+Filter operator returns tiddlers from the list that have a non-zero changecount.
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.haschanged = function(source,operator,options) {
 	var results = [];
 	if(operator.prefix === "!") {

core/modules/filters/indexes.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/indexes.js
 type: application/javascript
 module-type: filteroperator
+
+Filter operator for returning the indexes of a data tiddler
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.indexes = function(source,operator,options) {
 	var results = [];
 	source(function(tiddler,title) {

core/modules/filters/insertafter.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/insertafter.js
 type: application/javascript
 module-type: filteroperator
+
+Insert an item after another item in a list
+
 \*/
 
 "use strict";
 
+/*
+Order a list
+*/
 exports.insertafter = function(source,operator,options) {
 	var results = [];
 	source(function(tiddler,title) {
@@ -18,7 +24,7 @@ exports.insertafter = function(source,operator,options) {
 		if(pos !== -1) {
 			results.splice(pos,1);
 		}
-
+		// Insert the entry after the target marker
 		pos = results.indexOf(target);
 		if(pos !== -1) {
 			results.splice(pos+1,0,operator.operand);

core/modules/filters/insertbefore.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/insertbefore.js
 type: application/javascript
 module-type: filteroperator
+
+Insert an item before another item in a list
+
 \*/
 
 "use strict";
 
+/*
+Order a list
+*/
 exports.insertbefore = function(source,operator,options) {
 	var results = [];
 	source(function(tiddler,title) {
@@ -18,7 +24,7 @@ exports.insertbefore = function(source,operator,options) {
 		if(pos !== -1) {
 			results.splice(pos,1);
 		}
-
+		// Insert the entry before the target marker
 		pos = results.indexOf(target);
 		if(pos !== -1) {
 			results.splice(pos,0,operator.operand);

core/modules/filters/is.js

@@ -2,6 +2,9 @@
 title: $:/core/modules/filters/is.js
 type: application/javascript
 module-type: filteroperator
+
+Filter operator for checking tiddler properties
+
 \*/
 
 "use strict";
@@ -16,6 +19,9 @@ function getIsFilterOperators() {
 	return isFilterOperators;
 }
 
+/*
+Export our filter function
+*/
 exports.is = function(source,operator,options) {
 	// Dispatch to the correct isfilteroperator
 	var isFilterOperators = getIsFilterOperators();

core/modules/filters/is/binary.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/is/binary.js
 type: application/javascript
 module-type: isfilteroperator
+
+Filter function for [is[binary]]
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.binary = function(source,prefix,options) {
 	var results = [];
 	if(prefix === "!") {

core/modules/filters/is/blank.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/is/blank.js
 type: application/javascript
 module-type: isfilteroperator
+
+Filter function for [is[blank]]
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.blank = function(source,prefix,options) {
 	var results = [];
 	if(prefix === "!") {

core/modules/filters/is/current.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/is/current.js
 type: application/javascript
 module-type: isfilteroperator
+
+Filter function for [is[current]]
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.current = function(source,prefix,options) {
 	var results = [],
 		currTiddlerTitle = options.widget && options.widget.getVariable("currentTiddler");

core/modules/filters/is/draft.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/is/draft.js
 type: application/javascript
 module-type: isfilteroperator
+
+Filter function for [is[draft]] analagous to [has[draft.of]]
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.draft = function(source,prefix,options) {
 	var results = [];
 	if(prefix === "!") {

core/modules/filters/is/image.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/is/image.js
 type: application/javascript
 module-type: isfilteroperator
+
+Filter function for [is[image]]
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.image = function(source,prefix,options) {
 	var results = [];
 	if(prefix === "!") {

core/modules/filters/is/missing.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/is/missing.js
 type: application/javascript
 module-type: isfilteroperator
+
+Filter function for [is[missing]]
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.missing = function(source,prefix,options) {
 	var results = [];
 	if(prefix === "!") {

core/modules/filters/is/orphan.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/is/orphan.js
 type: application/javascript
 module-type: isfilteroperator
+
+Filter function for [is[orphan]]
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.orphan = function(source,prefix,options) {
 	var results = [],
 		orphanTitles = options.wiki.getOrphanTitles();

core/modules/filters/is/shadow.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/is/shadow.js
 type: application/javascript
 module-type: isfilteroperator
+
+Filter function for [is[shadow]]
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.shadow = function(source,prefix,options) {
 	var results = [];
 	if(prefix === "!") {

core/modules/filters/is/system.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/is/system.js
 type: application/javascript
 module-type: isfilteroperator
+
+Filter function for [is[system]]
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.system = function(source,prefix,options) {
 	var results = [];
 	if(prefix === "!") {

core/modules/filters/is/tag.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/is/tag.js
 type: application/javascript
 module-type: isfilteroperator
+
+Filter function for [is[tag]]
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.tag = function(source,prefix,options) {
 	var results = [],
 		tagMap = options.wiki.getTagMap();

core/modules/filters/is/tiddler.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/is/tiddler.js
 type: application/javascript
 module-type: isfilteroperator
+
+Filter function for [is[tiddler]]
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.tiddler = function(source,prefix,options) {
 	var results = [];
 	if(prefix === "!") {

core/modules/filters/is/variable.js

@@ -2,10 +2,16 @@
 title: $:/core/modules/filters/is/variable.js
 type: application/javascript
 module-type: isfilteroperator
+
+Filter function for [is[variable]]
+
 \*/
 
 "use strict";
 
+/*
+Export our filter function
+*/
 exports.variable = function(source,prefix,options) {
 	var results = [];
 	if(prefix === "!") {

core/modules/filters/json-ops.js

@@ -2,6 +2,9 @@
 title: $:/core/modules/filters/json-ops.js
 type: application/javascript
 module-type: filteroperator
+
+Filter operators for JSON operations
+
 \*/
 
 "use strict";
@@ -126,6 +129,9 @@ exports["jsondelete"] = function(source,operator,options) {
 	return results;
 };
 
+/*
+Given a JSON data structure and an array of index strings, return an array of the string representation of the values at the end of the index chain, or "undefined" if any of the index strings are invalid
+*/
 function getDataItemValueAsStrings(data,indexes) {
 	// Get the item
 	var item = getDataItem(data,indexes);
@@ -133,6 +139,9 @@ function getDataItemValueAsStrings(data,indexes) {
 	return convertDataItemValueToStrings(item);
 }
 
+/*
+Given a JSON data structure and an array of index strings, return an array of the string representation of the keys of the item at the end of the index chain, or "undefined" if any of the index strings are invalid
+*/
 function getDataItemKeysAsStrings(data,indexes) {
 	// Get the item
 	var item = getDataItem(data,indexes);
@@ -140,6 +149,9 @@ function getDataItemKeysAsStrings(data,indexes) {
 	return convertDataItemKeysToStrings(item);
 }
 
+/*
+Return an array of the string representation of the values of a data item, or "undefined" if the item is undefined
+*/
 function convertDataItemValueToStrings(item) {
 	// Return the item as a string
 	if(item === undefined) {
@@ -170,6 +182,9 @@ function convertDataItemValueToStrings(item) {
 	return [item.toString()];
 }
 
+/*
+Return an array of the string representation of the keys of a data item, or "undefined" if the item is undefined
+*/
 function convertDataItemKeysToStrings(item) {
 	// Return the item as a string
 	if(item === undefined) {
@@ -223,6 +238,10 @@ function getItemAtIndex(item,index) {
 	}
 }
 
+/*
+Traverse the index chain and return the item at the specified depth.
+Returns the item at the end of the traversal, or undefined if traversal fails.
+*/
 function traverseIndexChain(data,indexes,stopBeforeLast) {
 	if(indexes.length === 0 || (indexes.length === 1 && indexes[0] === "")) {
 		return data;
@@ -241,38 +260,47 @@ function traverseIndexChain(data,indexes,stopBeforeLast) {
 	return item;
 }
 
+/*
+Given a JSON data structure and an array of index strings, return the value at the end of the index chain, or "undefined" if any of the index strings are invalid
+*/
 function getDataItem(data,indexes) {
 	return traverseIndexChain(data,indexes,false);
 }
 
+/*
+Given a JSON data structure, an array of index strings and a value, return the data structure with the value added at the end of the index chain. If any of the index strings are invalid then the JSON data structure is returned unmodified. If the root item is targetted then a different data object will be returned
+*/
 function setDataItem(data,indexes,value) {
 	// Ignore attempts to assign undefined
 	if(value === undefined) {
 		return data;
 	}
-
+	// Check for the root item
 	if(indexes.length === 0 || (indexes.length === 1 && indexes[0] === "")) {
 		return value;
 	}
-
+	// Traverse the JSON data structure using the index chain up to the parent
 	var current = traverseIndexChain(data,indexes,true);
 	if(current === undefined) {
 		// Return the original JSON data structure if any of the index strings are invalid
 		return data;
 	}
-
+	// Add the value to the end of the index chain
 	var lastIndex = indexes[indexes.length - 1];
 	if(Array.isArray(current)) {
 		lastIndex = $tw.utils.parseInt(lastIndex);
 		if(lastIndex < 0) { lastIndex = lastIndex + current.length };
 	}
-
+	// Only set indexes on objects and arrays
 	if(typeof current === "object") {
 		current[lastIndex] = value;
 	}
 	return data;
 }
 
+/*
+Given a JSON data structure and an array of index strings, return the data structure with the item at the end of the index chain deleted. If any of the index strings are invalid then the JSON data structure is returned unmodified. If the root item is targetted then the JSON data structure is returned unmodified.
+*/
 function deleteDataItem(data,indexes) {
 	// Check for the root item - don't delete the root
 	if(indexes.length === 0 || (indexes.length === 1 && indexes[0] === "")) {