動態(tài)加載js腳本函數(shù)封裝
優(yōu)點：js代碼加載不阻塞瀏覽器其他的執(zhí)行
function loadScript(url,fn){
var oScript = document.createElement('script');
script.src=url;
document.getElementsByTagName('head')[0].appendChild(oScript);
if(window.addEventListener){//高版本瀏覽器
oScript.onload = function(){
fn && fn();
}
}else{//IE低版本瀏覽器
oScript.onreadystatechange = function(){
if(oScript.readyState='loaded' || oScript.readyState='compltet'){
oScript.onreadychange = null;
fn && fn();
}
}
}
}
