原生JS實現動態加載js文件并在加載成功后執行回調函數的方法

function loadScript(src, callback) {
 var script = document.createElement('script'),
 head = document.getElementsByTagName('head')[0];
 script.type = 'text/javascript';
 script.charset = 'UTF-8';
 script.src = src;
 if (script.addEventListener) {
 script.addEventListener('load', function () {
 callback();
 }, false);
 } else if (script.attachEvent) {
 script.attachEvent('onreadystatechange', function () {
 var target = window.event.srcElement;
 if (target.readyState == 'loaded') {
 callback();
 }
 });
 }
 head.appendChild(script);
}

loadScript('http://cdn.staticfile.org/jquery/1.6.2/jquery.min.js',function(){
 console.log('onload');
});