I'm trying to do something AFTER a script is completely loaded. (IE8)

Script I use for testing: http://ajax.googleapis.com/ajax/libs/jquery/1.5.1/jquery.min.js
and the invalid one: http://ajax.googleapis.com/ajax/libs/jquery/1.5.1/jquery.minaaaaaaaa.js

The code...

var script = create the element and append to head...

// this works fine with FF/Chrome/...
script.onload = function() {alert('script loading complete');}
script.onerror = function() {alert('error loading script');}

// and for IE
script.onreadystatechange = function() {
    // this will alert 1.loading 2.loaded
    alert(this.readyState);

    // this never works
    if(this.readyState == 'complete') {alert('script loading complete');}

    // this works with either a valid or INVALID url
    else if(this.readyState == 'loaded') {alert('script loaded');}
};

In my case, the "complete" never shows, the "loaded" shows even if a url is invalid. So there's no way to tell if a script is CORRECTLY loaded UNDER IE.

Am I doing something wrong? How come I never get the complete state?

UPDATE

OK, I just read some articles and it seems that readystate is not a reliable way to detect script loading.

So is there another way to do so? without jQuery, but pure Javascript.