待研究

	// 动态加载script
	$.load_script = function(xyUrl, callback) {
		var head = doc.getElementsByTagName(‘head‘)[0];
		var script = doc.createElement(‘script‘);
		script.type = ‘text/javascript‘;
		script.src = xyUrl;
		// 借鉴了jQuery的script跨域方法
		script.onload = script.onreadystatechange = function() {
			if ((!this.readyState || this.readyState === "loaded" || this.readyState === "complete")) {
				callback && callback();
				// Handle memory leak in IE
				script.onload = script.onreadystatechange = null;
				if (head && script.parentNode) {
					head.removeChild(script);
				}
			}
		};
		// Use insertBefore instead of appendChild to circumvent an IE6 bug.
		head.insertBefore(script, head.firstChild);
	};