Added support for elseif semantics, and a new comment tag.

For if, else if, else use: {{if a}}...{{else b}}...{{else}}...{{/if}}
For comments within templates, use {{! Here is my comment }}.
Added a new sample: samplesCore/condition.html, to illustrate use of these
template tags.

demos/samplesCore/conditional.html

@@ -0,0 +1,43 @@
+<!--
+This sample illustrates use of conditional template tags {{if}} and {{else}}.
+The comment tag {{! }} is also shown.
+-->
+
+<script src="http://code.jquery.com/jquery.js"></script>
+<script src="../../jquery.tmpl.js" type="text/javascript"></script>
+<script>
+$(function(){
+	$( "#movieTemplate" )
+	.tmpl( movies )
+	.appendTo( "#movieList" );
+});
+
+var movies = [
+	{ Name: "Meet Joe Black", Languages: "French", Subtitles: "English" },
+	{ Name: "The Mighty", Subtitles: "French and Spanish" },
+	{ Name: "The Mighty" },
+	{ Name: "City Hunter", Languages: "Mandarin and Cantonese" }
+];
+</script>
+
+<script id="movieTemplate" type="text/x-jquery-tmpl"> 
+	<li>${Name}
+
+		{{if Languages}}
+
+			(Alternative languages: ${Languages}).
+
+		{{else Subtitles}} {{! Note that the 'else' tag with a parameter behaves as 'else if' }}
+
+			(Original language only. Subtitles in ${Subtitles}).
+
+		{{else}} {{! The 'else' tag with no parameter behaves as 'else' }}
+
+			(Original version only, without subtitles).
+
+		{{/if}}
+
+	</li>
+</script>
+
+<ul id="movieList"></ul>

jquery.tmpl.js

@@ -4,7 +4,7 @@
  * Dual licensed under the MIT or GPL Version 2 licenses.
  */
 (function( jQuery, undefined ){
-	var oldManip = jQuery.fn.domManip, tmplItmAtt = "_tmplitem", htmlExpr = /^[^<]*(<[\w\W]+>)[^>]*$/,
+	var oldManip = jQuery.fn.domManip, tmplItmAtt = "_tmplitem", htmlExpr = /^[^<]*(<[\w\W]+>)[^>]*$|{{! /,
 		newTmplItems = {}, wrappedItems = {}, appendToTmplItems, topTmplItem = { key: 0, data: {} }, itemKey = 0, cloneIndex = 0, stack = [];
 
 	function newTmplItem( options, parentItem, fn, data ) {
@@ -226,14 +226,21 @@
 				close: "}"
 			},
 			"else": {
-				open: "}else{"
+				_default: { $1: "true" },
+				open: "}else if(($notnull_1) && $1a){"
 			},
 			"html": {
+				// Unecoded expression evaluation. 
 				open: "if($notnull_1){_.push($1a);}"
 			},
 			"=": {
+				// Encoded expression evaluation. Abbreviated form is ${}.
 				_default: { $1: "$data" },
 				open: "if($notnull_1){_.push($.encode($1a));}"
+			},
+			"!": {
+				// Comment tag. Skipped by parser
+				open: ""
 			}
 		},
 
@@ -331,12 +338,12 @@
 						expr = parens ? (target.indexOf(".") > -1 ? target + parens : ("(" + target + ").call($item" + args)) : target;
 						exprAutoFnDetect = parens ? expr : "(typeof(" + target + ")==='function'?(" + target + ").call($item):(" + target + "))";
 					} else {
-						expr = def["$1"] || "null";
+						exprAutoFnDetect = expr = def["$1"] || "null";
 					}
 					fnargs = unescape( fnargs );
 					return "');" + 
 						tag[ slash ? "close" : "open" ]
-							.split( "$notnull_1" ).join( "typeof(" + target + ")!=='undefined' && (" + target + ")!=null" )
+							.split( "$notnull_1" ).join( target ? "typeof(" + target + ")!=='undefined' && (" + target + ")!=null" : "true" )
 							.split( "$1a" ).join( exprAutoFnDetect )
 							.split( "$1" ).join( expr )
 							.split( "$2" ).join( fnargs ?