Begin a common WordPress Backbone helpers file.

Moves the `wp.template` helper to `wp-backbone.js`.



git-svn-id: http://core.svn.wordpress.org/trunk@24358 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/js/wp-backbone.js

@@ -0,0 +1,29 @@
+window.wp = window.wp || {};
+
+(function ($) {
+	var template;
+	/**
+	 * wp.template( id )
+	 *
+	 * Fetches a template by id.
+	 *
+	 * @param  {string} id   A string that corresponds to a DOM element with an id prefixed with "tmpl-".
+	 *                       For example, "attachment" maps to "tmpl-attachment".
+	 * @return {function}    A function that lazily-compiles the template requested.
+	 */
+	template = wp.template = _.memoize(function ( id ) {
+		var compiled,
+			options = {
+				evaluate:    /<#([\s\S]+?)#>/g,
+				interpolate: /\{\{\{([\s\S]+?)\}\}\}/g,
+				escape:      /\{\{([^\}]+?)\}\}(?!\})/g,
+				variable:    'data'
+			};
+
+		return function ( data ) {
+			compiled = compiled || _.template( $( '#tmpl-' + id ).html(), null, options );
+			return compiled( data );
+		};
+	});
+
+}(jQuery));