Support a class to be automatically added to transformed elements

core/modules/widgets/element.js

@@ -46,6 +46,10 @@ ElementWidget.prototype.render = function(parent,nextSibling) {
 	var mappedTag = this.getVariable("tv-map-" + this.tag);
 	if(mappedTag) {
 		this.tag = mappedTag.trim();
+		var mappedClass = this.getVariable("tv-map-" + this.tag + "-class");
+		if(mappedClass) {
+			this.setAttribute("class",mappedClass.trim() + (this.getAttribute("class") ? " " + this.getAttribute("class") : ""));
+		}
 	}
 	// Select the namespace for the tag
 	var XHTML_NAMESPACE = "http://www.w3.org/1999/xhtml",

editions/test/tiddlers/tests/data/element-mapping/Basic.tid

@@ -7,12 +7,13 @@ title: Output
 
 \whitespace trim
 
-<!-- Map <p> to <div> -->
+<!-- Map <p> to <div>, adding the class my-class -->
 \define tv-map-p() div
+\define tv-map-p-class() my-class
 
 This is a paragraph
 
 +
 title: ExpectedResult
 
-<div>This is a paragraph</div>
+<div class="my-class">This is a paragraph</div>