判断javascript加载完成的方法

function include_js(file) {
var _doc = document.getElementsByTagName('head')[0];
var js = document.createElement('script');
js.setAttribute('type', 'text/javascript');
js.setAttribute('src', file);
_doc.appendChild(js);
if (!/*@cc_on!@*/0) { //if not IE
    //Firefox2、Firefox3、Safari3.1+、Opera9.6+ support js.onload
    js.onload = function () {
        alert('Firefox2、Firefox3、Safari3.1+、Opera9.6+ support js.onload');
    }
} else {
    //IE6、IE7 support js.onreadystatechange
    js.onreadystatechange = function () {
        if (js.readyState == 'loaded' || js.readyState == 'complete') {
            alert('IE6、IE7 support js.onreadystatechange');
        }
    }
}
return false;
}
//execution function
include_js('http://www.planabc.net/wp-includes/js/jquery/jquery.js');