odj.js

/**
 * odj.js - On-Demand JavaScript
 *
 * Based on jsr_class.js:
 * http://www.xml.com/pub/a/2005/12/21/json-dynamic-script-tag.html
 *
 * License:
 * Copyright (c) 2006 Kyo Nagashima <kyo@hail2u.net>
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

function onDemandJavaScript() {
  this.head = document.getElementsByTagName('head').item(0);
}

onDemandJavaScript.prototype = {
  request: function (url, callback, callbackParamName) {
    var self = this;
    var i = onDemandJavaScript.counter++;

    onDemandJavaScript.jsonpCallbacks[i] = function() {
      delete onDemandJavaScript.jsonpCallbacks[i];
      callback.apply(self, arguments);
    }

    var script = document.createElement("script");
    script.setAttribute("type", "text/javascript");
    script.setAttribute("src", url + (url.indexOf('?') > 0 ? '&' : '?') + 'nocache=' + (new Date()).getTime() + '&' + callbackParamName + '=' + encodeURIComponent("onDemandJavaScript.jsonpCallbacks[" + i + "]"));
    script.setAttribute("charset", "UTF-8");
    this.head.appendChild(script);
  }
};

onDemandJavaScript.counter = 0;
onDemandJavaScript.jsonpCallbacks = [];