Simple JavaSctipt Inheritance Module - ASM Compliant

class.js

/**
 * Class Module (No Dependencies)
 */
define(function() {

    // Set to true when creating New Prototype to ensure "_constructor" is not executed
    var extending = false;
    
    // Base Constructor
    var Class = function() {};

    // Create Subclass
    Class.extend = function(properties) {
        // New Constructor
        function Class() {
            // Delegate to _constructor function
            if(!extending && this._constructor) {
                this._constructor.apply(this, arguments);
            }
        };

        // New Prototype
        extending = true;
        var prototype = new this();
        extending = false;
        
        // Set Constructor
        prototype.constructor = Class;
        
        // Set Super
        prototype._super = this.prototype;
        
        // Set Prototype
        Class.prototype = prototype;
        
        // Set Class Functions
        Class.mixin = this.mixin;
        Class.extend = this.extend;
               
        // Add Properties 
        Class.mixin(properties);

        return Class;
    };
    
    // Extend Class Prototype
    Class.mixin = function(properties) {
        extend(this.prototype, properties);
    };
    
    // Extend Instance
    Class.prototype.mixin = function(properties) {
        extend(this, properties);
    };
    
    // Extend Utility (to ensure no external dependencies)
    function extend(dest, src) {
        if (src) {
            for (var prop in src) {
                if (src.hasOwnProperty(prop)) {
                    dest[prop] = src[prop]
                }
            }
        }
        return dest
    }

    // Export "Class" Constructor
    return Class;
    
});