页面动态加载js文件

function loadJS(url, onload) {
var domscript = document.createElement('script');
domscript.src = url;
domscript.charset = 'utf-8';
if (onload) {
domscript.onloadDone = false;
domscript.onload = onload;
domscript.onreadystatechange = function () {
if ("loaded" === domscript.readyState && domscript.onloadDone) {
domscript.onloadDone = true;
domscript.onload();
domscript.removeNode(true);
}
};

}
document.getElementsByTagName('head')[0].appendChild(domscript);
}