Application starter

start.app.js

/**
 * start.app.js
 *
 * Application starter. Will use it on my website :)
 *
 * @author Saneyuki Tadokoro (@Saneyan or @jSaneyan) <post@saneyuki.gfunction.com>
*/

//
// Use strict mode
//
"use strict";


//
// Define application
//
var Application = function( navi, doc ){

  // Regular express for file path
  var pathRegExp = /^$/;
  
  /*
   * Require a script (Local scope)
  */
  var _require = function( src, success, error ){
    var script = doc.createElement( 'script' );
    script.type = 'text/javascript';
    script.src = src;
    script.onload = success;
    script.onerror = error;
    doc.getElementsByTagName( 'head' ).item( 0 ).appendChild( script );
  };
  
  // Application instance will be in this variable
  var _instance;

  /*
   * Application constructor
  */
  var _constructor = function(){
    //console.log( "Created 'Application' instance." );
  };

  _constructor.prototype = {
    
      /*
       * Try to start Dart VM
      */
      startDart: function(){
        if( navi.webkitStartDart ){
          if( !navi.webkitStartDart() )
            throw "Could not startup Dart VM <start.app.js>";
        }
        else{
          throw "This browser doesn't have Dart VM <start.app.js>";
        }
      }
      
      /*
       * Require script
       * @param   string path (Must be file path)
       * @param   function success <optional> (Will be called when the script is loaded successfully)
       * @param   function error <optional> (Will be called when it cannot load the script)
      */
    , require: function( path, success, error ){
        path = path.replace( pathRegExp, '' );
        
        _require( path, success, function(){
          if( typeof error == 'function' )
            error();
            
          throw "Could not load a script '" + path + "' <start.app.js>";
        });
      }
  };

  _constructor.getInstance = function(){
    if( !( _instance instanceof this ) )
      _instance = new this();

    return _instance;
  };

  return _constructor;

}( navigator, document );



window.addEventListener( 'load', function(){
  
  // Get 'Application' instance
  var app = Application.getInstance();

  try{
    // Try to start Dart VM
    app.startDart();
  } catch( e ){
    // Otherwise, try to load and start compatible scripts
    var _success = function(){ console.log( "Success :)" ); };
    var _error = function(){ console.log( "Error :(" ); };

    app.require( 'scripts/js/compatible.app.js', _success, _error );
  }

  // Singleton pattern test
  var app2 = Application.getInstance();

  // Result...
  console.log( "app === app2? " + ( app === app2 ) );   // app === app2? true

});