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Mediator pattern (HB Stone)

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Somewhat tweaked

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  1. <!doctype html>
  2. <html lang="en">
  3. <head>
  4.   <meta charset="utf-8">
  5.   <title></title>
  6.   <meta name="description" content="">
  7.   <script>
  8.     Mediator = function () {
  9.       var debug = function (m) {
  10.             console.info(m)
  11.           },
  12.  
  13.           components = {},
  14.  
  15.           addComponent = function (name, component, replaceDuplicate) {
  16.             if (name in components) {
  17.               if (replaceDuplicate) {
  18.                 removeComponent(name);
  19.               }
  20.               else {
  21.                 throw new Error('Mediator name conflict: ' + name);
  22.               }
  23.             }
  24.             components[name] = component;
  25.           },
  26.  
  27.           broadcast = function (event, args, source) {
  28.             var c, s,
  29.                 e = event || false,
  30.                 a = args || [];
  31.  
  32.             if (!e) { return; }
  33.  
  34.             for (c in components) {
  35.               if (typeof components[c]["on" + e] == "function") {
  36.                 try {
  37.                   s = source || components[c];
  38.                   components[c]["on" + e].apply(s, a);
  39.                 }
  40.                 catch (err) {
  41.                   debug(["Mediator error.", e, a, s, err].join(' '));
  42.                 }ac
  43.               }
  44.             }
  45.           },
  46.           removeComponent = function (name) {
  47.             if (name in components) { delete components[name]; }
  48.           },
  49.           getComponent = function (name) { return components[name] || false; },
  50.           contains = function (name) { return (name in components); };
  51.  
  52.       return {
  53.         name: "Mediator",
  54.         broadcast: broadcast,
  55.         add: addComponent,
  56.         rem: removeComponent,
  57.         get: getComponent,
  58.         has: contains
  59.       };
  60.     }();
  61.  
  62.     Mediator.add('TestObject', function () {
  63.       var someNumber = 0,    // sample variable
  64.           someString = 'another sample variable';
  65.  
  66.       return {
  67.         onInitialize: function () {
  68.                   console.debug(this)
  69.           // this.name is automatically assigned by the Mediator
  70.           console.log(this.name + " initialized.");
  71.         },
  72.         onFakeEvent: function () {
  73.           someNumber++;
  74.           console.log("Handled " + someNumber + " times!");
  75.         },
  76.         onSetString: function (str) {
  77.           someString = str;
  78.           console.log('Assigned ' + someString);
  79.         }
  80.       }
  81.     }());
  82.  
  83.   </script>
  84.  
  85. </head>
  86. <body>
  87.  
  88.   <script>
  89.     Mediator.broadcast("Initialize"); // alerts "TestObject initialized"
  90.     Mediator.broadcast('FakeEvent'); // alerts "Handled 1 times!" (I know, bad grammar)
  91.     Mediator.broadcast('SetString', ['test string']); // alerts "Assigned test string"
  92.     Mediator.broadcast('FakeEvent'); // alerts "Handled 2 times!"
  93.     Mediator.broadcast('SessionStart'); // this call is safely ignored
  94.     Mediator.broadcast('Translate', ['this is also safely ignored']);
  95.   </script>
  96.  
  97. </body>
  98. </html>

URL: http://arguments.callee.info/2009/05/18/javascript-design-patterns--mediator/

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