Part two of turning the rabbit hole inside out

core/modules/tiddler.js

@@ -0,0 +1,34 @@
+/*\
+title: $:/core/modules/tiddler.js
+type: application/javascript
+module-type: tiddlermethod
+
+Extension methods for the $tw.Tiddler object
+
+\*/
+(function(){
+
+/*jslint node: true, browser: true */
+/*global $tw: false */
+"use strict";
+
+exports.hasTag = function(tag) {
+	return this.fields.tags && this.fields.tags.indexOf(tag) !== -1;
+};
+
+exports.getFieldString = function(field) {
+	var value = this.fields[field];
+	// Check for a missing field
+	if(value === undefined) {
+		return undefined;
+	}
+	// Parse the field with the associated plugin (if any)
+	var fieldPlugin = $tw.Tiddler.fieldPlugins[field];
+	if(fieldPlugin) {
+		return fieldPlugin.stringify.call(this,value);
+	} else {
+		return value.toString();
+	}
+};
+
+})();