Limited implementation of external text tiddlers in the browser

Triggered by the discussion in #1917

core/modules/parsers/wikiparser/wikiparser.js

@@ -26,6 +26,23 @@ Attributes are stored as hashmaps of the following objects:
 
 var WikiParser = function(type,text,options) {
 	this.wiki = options.wiki;
+	var self = this;
+	// Check for an externally linked tiddler
+	if($tw.browser && options._canonical_uri) {
+		$tw.utils.httpRequest({
+			url: options._canonical_uri,
+			type: "GET",
+			callback: function(err,data) {
+				if(!err) {
+					var tiddlers = self.wiki.deserializeTiddlers(".tid",data,self.wiki.getCreationFields())
+					if(tiddlers) {
+						self.wiki.addTiddlers(tiddlers);
+					}
+				}
+			}
+		});
+		text = "Loading external text from ''" + options._canonical_uri + "''\n\nIf this message doesn't disappear you may be using a browser that doesn't support external text in this configuration. See http://tiddlywiki.com/#ExternalText";
+	}
 	// Initialise the classes if we don't have them already
 	if(!this.pragmaRuleClasses) {
 		WikiParser.prototype.pragmaRuleClasses = $tw.modules.createClassesFromModules("wikirule","pragma",$tw.WikiRuleBase);

core/modules/utils/dom/browser.js

@@ -43,7 +43,7 @@ exports.convertStyleNameToPropertyName = function(styleName) {
 	// Convert it by first removing any hyphens
 	var propertyName = $tw.utils.unHyphenateCss(styleName);
 	// Then check if it needs a prefix
-	if(document.body.style[propertyName] === undefined) {
+	if($tw.browser && document.body.style[propertyName] === undefined) {
 		var prefixes = ["O","MS","Moz","webkit"];
 		for(var t=0; t<prefixes.length; t++) {
 			var prefixedName = prefixes[t] + propertyName.substr(0,1).toUpperCase() + propertyName.substr(1);

core/modules/utils/dom/http.js

@@ -58,7 +58,11 @@ exports.httpRequest = function(options) {
 	if(data && !$tw.utils.hop(headers,"Content-type")) {
 		request.setRequestHeader("Content-type","application/x-www-form-urlencoded; charset=UTF-8");
 	}
-	request.send(data);
+	try {
+		request.send(data);
+	} catch(e) {
+		options.callback(e);
+	}
 	return request;
 };
 

core/templates/canonical-uri-external-text.tid

@@ -0,0 +1,10 @@
+title: $:/core/templates/canonical-uri-external-text
+
+<!--
+
+This template is used to assign the ''_canonical_uri'' field to external text files.
+
+Change the `./text/` part to a different base URI. The URI can be relative or absolute.
+
+-->
+./text/<$view field="title" format="doubleurlencoded"/>.tid

editions/prerelease/tiddlers/Release 5.1.10.tid

@@ -28,6 +28,17 @@ The new [[Résumé Builder Edition]] by @inmysocks is a custom edition to guide
 
 The new [[Text-Slicer Edition]] is a custom edition with tools to help advanced users slice longer texts up into individual tiddlers.
 
+!! External Text Tiddlers
+
+Limited support for tiddlers stored in external `.tid` files:
+
+* standalone TiddlyWiki HTML files with external text tiddlers can be built under Node.js
+* wikis with external text tiddlers can be worked with in the browser, automatically lazily loading the content of external text tiddlers when it is first referenced
+** saving changes in the browser doesn't work as expected: if edited, the external text tiddler is replaced with an ordinary tiddler
+** lazy loading of external text tiddlers doesn't work in Chrome when viewing the TiddlyWiki HTML file on a ''file:'' URI; it works OK in Firefox. It works on an HTTP URI on all browsers
+
+See [[Alice in Wonderland]] for an example. Try opening it without a network connection.
+
 ! Other Improvements
 
 !! Translation Improvements

editions/tw5.com/tiddlywiki.info

@@ -20,8 +20,10 @@
 	"build": {
 		"index": [
 			"--savetiddlers","[tag[external-image]]","images",
+			"--rendertiddlers","[tag[external-text]]","$:/core/templates/tid-tiddler","text","text/plain",".tid",
 			"--setfield","[tag[external-image]]","_canonical_uri","$:/core/templates/canonical-uri-external-image","text/plain",
-			"--setfield","[tag[external-image]]","text","","text/plain",
+			"--setfield","[tag[external-text]]","_canonical_uri","$:/core/templates/canonical-uri-external-text","text/plain",
+			"--setfield","[tag[external-image]] [tag[external-text]]","text","","text/plain",
 			"--rendertiddler","$:/core/save/all","index.html","text/plain"],
 		"encrypted": [
 			"--password", "password",