John Resig's Class OO Plugin

John Resig's Class OO Plugin

by cjgaudin

JavaScript

/* Simple JavaScript Inheritance
  * By John Resig http://ejohn.org/
  * MIT Licensed.
  */
 // Inspired by base2 and Prototype
 (function(){
   var initializing = false, fnTest = /xyz/.test(function(){xyz;}) ? /\b_super\b/ : /.*/;
 
  // The base Class implementation (does nothing)
   this.Class = function(){};
   
  // Create a new Class that inherits from this class
   Class.extend = function(prop) {
     var _super = this.prototype;
     
    // Instantiate a base class (but only create the instance,
     // don't run the init constructor)
     initializing = true;
     var prototype = new this();
     initializing = false;
     
    // Copy the properties over onto the new prototype
     for (var name in prop) {
       // Check if we're overwriting an existing function
       prototype[name] = typeof prop[name] == "function" && 
        typeof _super[name] == "function" && fnTest.test(prop[name]) ?
         (function(name, fn){
           return function() {
             var tmp = this._super;
             
            // Add a new ._super() method that is the same method
             // but on the super-class
             this._super = _super[name];
             
            // The method only need to be bound temporarily, so we
             // remove it when we're done executing
             var ret = fn.apply(this, arguments);        
            this._super = tmp;
             
            return ret;
           };
         })(name, prop[name]) :
         prop[name];
     }
     
    // The dummy class constructor
     function Class() {
       // All construction is actually done in the init method
       if ( !initializing && this.init )
         this.init.apply(this, arguments);
     }
     
    // Populate our constructed prototype object
     Class.prototype = prototype;
     
    // Enforce the constructor to be what we expect
     Class.prototype.constructor = Class;
 
    // And make this class extendable
     Class.extend = arguments.callee;
   ...