As soon as possible - simple asynchronous script loading library

asap.js

// ASAP Library

// use case
/*
		add omniture to registry
		omniture tags are waiting to fire
		asap loads omniture asynchronously
		page waits for omniture to be ready
		omniture loads
		asap announces omniture is ready
		omniture fires off tags
*/
(function (undefined) {
  'use strict';

  var registry = {};

  function register (name) {
    if (registry[name] === undefined) {
      registry[name] = {
        name: name,
        callbacks: [],
        results: {},
        ready: false
      };
    }
    return registry[name];
  }

  function regQueue (names, entryName) {
    var name = names.shift();
    var myEntry = asap(name);

    myEntry.then(function (results) {
      for (var r in results) {
        register(entryName).results[r] = results[r];
      }

      if (names.length) {
        regQueue(names, entryName);
      } else {
        asap(entryName).resolve();
      }
    });
  }

  function asap () {
    // TODO: support comma/space-separated string
    var regEntry;
    var args = Array.prototype.slice.call(arguments);
  	var name = args.sort().join(',').toLowerCase();

    if (args.length === 0) {
      throw 'No name to register';
    }

    regEntry = register(name);

    if (args.length > 1) {
      regQueue(args, name);
    }

    var api = {
      'resolve': function (val, refresh) {
        if (refresh || !regEntry.ready) {
          // resolving: set ready to true and triggering event with message
          regEntry.ready = true;
          if (val != null) {
            regEntry.results[regEntry.name] = val;
          }
          // run callback queue
          for (var i = 0, j = regEntry.callbacks.length; i < j; i++) {
            // try {
            regEntry.callbacks[i](regEntry.results);
            // } catch (err) {}
          }
        }
        return api;
      },
      'then': function (cb) {
        if (typeof cb === 'function') {
          regEntry.callbacks.push(cb);

          if (regEntry.ready) {
            // try {
            cb(regEntry.results);
            // } catch (err) {}
          }
        }
        return api;
      }
    };
    return api;
  }

  asap.loadScript = function (url, id) {
    if (url) {
      var doc = document;
      var t = doc.createElement('script');
      var s = doc.getElementsByTagName('script')[0];

      if (id) {
        if (doc.getElementById(id)) {
          return;
        }
        t.id = id;
        t.onload = t.onreadystatechange = function () {
          t.onreadystatechange = t.onload = null;
          asap(id).resolve();
        };
      }

      t.type = 'text/javascript';
      // Keep script order!
      t.async = false;
      t.src = url;
      s.parentNode.insertBefore(t, s);
    }
  };

  this.asap = asap;
}).call(this);