异步加载js--- iframe加载完后 异步加载js

function(jsUrl,cb,async){
			var head = document.head || document.getElementsByTagName( "head" )[0] || document.documentElement;
			var script = document.createElement( "script" );
			if( async !== false ){ //异步
				script.async = "async";
				script.defer = "defer";
			}
			script.src = jsUrl;
			if(cb){
				try{
					script.onload = script.onreadystatechange = function( _eve, isAbort ) {
						if(isAbort || !script.readyState || /loaded|complete/.test( script.readyState )){
							// 清除ie状态否则ie版本不同会执行对此回调方法
							script.onload = script.onreadystatechange = null;
							script = undefined;
							if(!isAbort){//!isAbort = (success ok 200)
								cb();
							}
						}
						
					};
				}catch(e){}
			}
			head.insertBefore( script, head.firstChild ); 
		
		}

 

var frame = document.getElementById('app_comment_dlg_iframe');
		frame.onload = frame.onreadystatechange = function(_eve, isAbort) {
			if (isAbort || !frame.readyState
					|| /loaded|complete/.test(frame.readyState)) {
				frame.onload = frame.onreadystatechange = null;
				frame = undefined;
				if (!isAbort) {
					Comment.loadJs(CONST_COMMENT.BSFW_URL
							+ "/skins/js/messenger.js", function() {
						var _iframe = document.getElementById('app_comment_dlg_iframe');
						var messenger = Messenger.initInParent(_iframe);
						messenger.onmessage = function(data) {
							var res = eval('(' + data + ')');
							if (res.res_data) {
								if (res.is_close) {
									Comment.closeCommentDlg();
									alert(res.cause);
								} else {
									alert(res.cause);
								}
							} else {
								_iframe.style.height = data + 'px';
								divContain.style.height = data + 'px';
							}
						};
					});
				}
			}
		};