javascript resource loader

jsLoad-1.0.0.js

/*
 * Copyright © 2011 by Scott Perry
 * Released under the MIT License; its terms are at the end of this file.
 *
 * This file depends on:
 * • jQuery (tested against v1.4.2)
 *   http://jquery.com/
 *
 * Pages that include this file should load all their javascript files (other
 * than jQuery) by using jsLoad("path").
 *
 * Inspired by:
 *   http://code.google.com/speed/page-speed/docs/payload.html#DeferLoadingJS
 *
 ******************************************************************************
 */

// call this to load/queue your file
function jsLoad(script) {
  jsLoad_Scripts.push(script);

  if(jsLoad_Locked == 0) {
    jsLoad_Insert();
  }
}

// pending scripts
var jsLoad_Scripts = [];
// loaded scripts
var jsLoad_Loaded = [];
// global lock
var jsLoad_Locked = -1;

// add/evaluate a script
function jsLoad_Insert() {
  if(jsLoad_Scripts.length == 0) {
    // first run? then we're done.
    if(jsLoad_Locked == -1) {
      jsLoad_Locked = 0;
    }
    return;
  }

  script = jsLoad_Scripts.shift();
  // duplicate barrier
  if(jsLoad_Loaded.indexOf(script) != -1) {
    jsLoad_Insert();
    return;
  }
  jsLoad_Loaded.push(script);

  if(jsLoad_Locked == -1) {
    // document just finished loading
    var element = document.createElement("script");
    element.charset = "utf-8";
    element.type = "text/javascript";
    element.src = script;
    document.body.appendChild(element);

    // recurse
    jsLoad_Insert();
  } else {
    // document has finished loading, use serial XHRs to prevent a race
    if(jsLoad_Locked != 0) {
      return;
    }
    jsLoad_Locked = 1;

    $.ajax({
      type: "GET",
      url: script,
      dataType: "script",
      success: function(data) {
        // NOTE: script is automatically evaluated by jQuery
        // unlock and handle the next script
        jsLoad_Locked = 0;
        jsLoad_Insert();
      }
    });
  }
}

/*
 * when the document is loaded, insert pending js
 * NOTE: firing jsLoad_Insert for the first time after the document is ready can
 *       cause a race condition between scripts that depend on each other.
 */
if (window.addEventListener) {
  window.addEventListener("load", jsLoad_Insert, false);
} else if (window.attachEvent) {
  window.attachEvent("onload", jsLoad_Insert);
} else {
  window.onload = jsLoad_Insert;
}

/*
 * 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.
 */

jsLoad-1.0.0.min.js

function jsLoad_Insert(){if(jsLoad_Scripts.length==0){if(jsLoad_Locked==-1){jsLoad_Locked=0}return}script=jsLoad_Scripts.shift();if(jsLoad_Loaded.indexOf(script)!=-1){jsLoad_Insert();return}jsLoad_Loaded.push(script);if(jsLoad_Locked==-1){var a=document.createElement("script");a.charset="utf-8";a.type="text/javascript";a.src=script;document.body.appendChild(a);jsLoad_Insert()}else{if(jsLoad_Locked!=0){return}jsLoad_Locked=1;$.ajax({type:"GET",url:script,dataType:"script",success:function(a){jsLoad_Locked=0;jsLoad_Insert()}})}}function jsLoad(a){jsLoad_Scripts.push(a);if(jsLoad_Locked==0){jsLoad_Insert()}}var jsLoad_Scripts=[];var jsLoad_Loaded=[];var jsLoad_Locked=-1;if(window.addEventListener){window.addEventListener("load",jsLoad_Insert,false)}else if(window.attachEvent){window.attachEvent("onload",jsLoad_Insert)}else{window.onload=jsLoad_Insert}