动态加载js文件

function loadScript(url){var hd = document.getElementsByTagName(’head’)[0],js = document.createElement(’script’);js.src = url;js.type = “text/javascript”;if(js.addEventListener){js.addEventListener(”load”, function(){alert(’loaded’);}, false);}else if(js.attachEvent){js.attachEvent(”onreadystatechange”, function(){if(js.readyState === “loaded” || js.readyState === “complete”){alert(’loaded’);}});}hd.appendChild(js);}