Simple Class

simple-class.js

/* Simple JavaScript Inheritance
 * By John Resig http://ejohn.org/
 * MIT Licensed.
 * Modified for code readability and added bindMethods() feature.
 */
// Inspired by base2 and Prototype
var initializing = false;
var fnTest = /xyz/.test(function(){xyz;}) ? /\b_super\b/ : /.*/;

// The base Class implementation (does nothing)
var Class = function(){};

// Create a new Class that inherits from this class
Class.extend = function(props) {
    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;
    
    // Add the .bindMethods() method.
    if (!props.bindMethods) {
        props.bindMethods = function() {
            for (var name in this) {
                if (typeof this[name] === 'function') {
                    this[name] = this[name].bind(this);
                }
            }
        };
    }

    // Copy the properties over onto the new prototype
    for (var name in props) {
        
        var isOverridingExistingFunction = 
            typeof props[name] == "function" && 
            typeof _super[name] == "function" && 
            fnTest.test(props[name]);
        
        if (isOverridingExistingFunction) {
            prototype[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, props[name]);
        } else {
            prototype[name] = props[name];
        }
    }

    // The dummy class constructor
    function Class() {
        // All construction is actually done in the init method
        if ( !initializing && this.init ) {
            if (this.initialize) {
                this.initialize.apply(this, arguments);
            }
          this.init.apply(this, arguments);
        }
    }

    // Populate our constructed prototype object
    Class.prototype = prototype;

    // Enforce the constructor to be what we expect
    Class.constructor = Class;

    // And make this class extendable
    Class.extend = arguments.callee;

    return Class;
};
module.exports = Class;