Micro DynamicScript Snippet

micro.script.js

/*
by Composite (http://blog.hazard.kr)

reference -
http://stackoverflow.com/questions/4845762/onload-handler-for-script-tag-in-internet-explorer

Usage -
getScript('http://www.domain.com/js/myscript.js','utf-8').then(function(){
    myMethod('yay!');
});
getScript('script1.js').then(fn1).getScript('script2.js').then(fn2)...
*/
function getScript(url,enc){
    var head=document.getElementsByTagName('head')[0],script=document.createElement('script')
        ,_deff=function(){this.fn={};},done=false;
    _deff.prototype.then=function(done){
        if(typeof done === 'function') this.fn.done=done;
        return {getScript:getScript};
    };
    var get=new _deff();
    script.type="text/javascript";
    if(enc) script.charset=enc;
    script.onload=script.onreadystatechange=function(){
        var rs=this.readyState;
        if(done || (rs && rs !== "loaded" && rs !== "complete")) return;
        done=true;
        for(var x in get.fn) if(typeof get.fn[x] == 'function') get.fn[x].call(script);
        script.onload = script.onreadystatechange = null;
        if (head && script.parentNode) head.removeChild( script );
    };
    script.src=url;
    head.insertBefore( script, head.firstChild );
    return get;
}