gistfile1.js

/**
 * lucas' micro lazy loader.
 *
 * Super tiny lazy loader for external dependencies.  Features callbacks when 
 * individual scripts are loaded and when all scripts have finished loading.
 *
 * @todo (lucas) Use interval to check for load errors
 *
 * $l(
 *     [
 *         'http://plugins.jquery.com/files/labs_json.js_0.txt',
 *         [
 *             'http://code.jquery.com/jquery-1.4a1.min.js',
 *             function(src){
 *                 console.log('Loaded jquery 1.4 alpha 1 from '+src);
 *             }
 *         ]
 *     ],
 *     function(src_list){
 *         console.log('All sources loaded:');
 *         console.dir(src_list);
 *         alert('All sources loaded!');
 *     }
 * );
 *
 * @author Lucas Hrabovsky http://www.imlucas.com http://www.twitter.com/__lucas
 */

var $l = function(r, cb){
    var l = [],
        u = undefined,
        f = function(o){toString.call(o) === "[object Function]";},
        a = function(o){toString.call(o) === "[object Array]";},
        z = function(x){ // loads script with src=x.  calls c when complete.
            var d = document, s = d.createElement('script'), v = x, w = u;
            if(a(x)){
                v = x[0], w = x[1];
            }
            s.onload = s.onreadystatechange = function(){ 
                var s = this;
                if(!s.readyState||/de|te/.test(s.readyState)){
                    s.onload = s.onreadystatechange = null; 
                    if(f(w)){
                        w.apply(this, v);
                    }
                    l.push(v);
                    if(l.length == r.length){
                        cb.apply(this, l);
                    }
                } 
            };
            s.src = v;
            d.getElementsByTagName('head')[0].appendChild(s);
        };
    for(s in r){z(s);}
};