Add a function to check whether a tiddler has a given field

core/modules/macros/list.js

@@ -92,7 +92,7 @@ Create the tiddler macro needed to represent a given tiddler
 exports.createListElementMacro = function(title) {
 	// Check if the tiddler is a draft
 	var tiddler = this.wiki.getTiddler(title),
-		draft = tiddler ? $tw.utils.hop(tiddler.fields,"draft-of") : false;
+		draft = tiddler ? tiddler.hasField("draft-of") : false;
 	// Figure out the template to use
 	var template = this.params.template,
 		templateText = this.params.templateText;

core/modules/tiddler.js

@@ -16,6 +16,10 @@ exports.hasTag = function(tag) {
 	return this.fields.tags && this.fields.tags.indexOf(tag) !== -1;
 };
 
+exports.hasField = function(field) {
+	return $tw.utils.hop(this.fields,field);
+};
+
 exports.getFieldString = function(field) {
 	var value = this.fields[field];
 	// Check for a missing field