上代码:
这段代码放到HTML文档的</body>
标签之前(靠近HTML文档底部)。外部脚本的名称为defer.js
。
<script type="text/javascript"> function downloadJSAtOnload() {
var element = document.createElement("script");
element.src = "defer.js";
document.body.appendChild( element );
} if ( window.addEventListener ) {
window.addEventListener( "load", downloadJSAtOnload, false );
} else if ( window.attachEvent ) {
window.attachEvent( "onload", downloadJSAtOnload );
} else {
window.onload = downloadJSAtOnload;
}
</script>
参考:
http://www.cnblogs.com/yangyoucun/p/6337360.html#undefined