JavaScript继承

1、类式继承

//使subclass继承superclass

function extend(subclass, superclass){
    function F() {};
    F.prototype = superclass.prototype;
    subclass.prototype = new F();//类式继承
    subclass.prototype.constructor = subclass;
    
    subclass.superclass = superclass.prototype;
    if (superclass.prototype.constructor == Object.prototype.constructor){
        superclass.prototype.constructor = superclass;
    }
}

2、原型式继承

function clone(object) {

    function F() {};

    F.prototype = object.prototype;//原型继承

    return new F();

 }

3、掺元类

//用givingclass类来扩充receivingclass类

function augment(receivingclass, givingclass) {

    if (arguments[2]) {

        for (var i = 2, len = arguments.length; i < len; i += 1) {

            receivingclass.prototype[arguments[i]] = givingclass.prototype[arguments[i]];

        }  

    } else {

        for (methodName in givingclass.prototype) {

            if (!receivingclass.prototype[methodName]) {

                receivingclass.prototype[methodName] = givingclass.prototype[methodName];

            }

         }

    }

}

function extend(subclass, superclass){
    function F() {};
    F.prototype = superclass.prototype;
    subclass.prototype = new F();
    subclass.prototype.constructor = subclass;
    
    
    subclass.superclass = superclass.prototype;
    if (superclass.prototype.constructor == Object.prototype.constructor){
        superclass.prototype.constructor = superclass;
    }
}function extend(subclass, superclass){
    function F() {};
    F.prototype = superclass.prototype;
    subclass.prototype = new F();
    subclass.prototype.constructor = subclass;
    
    
    subclass.superclass = superclass.prototype;
    if (superclass.prototype.constructor == Object.prototype.constructor){
        superclass.prototype.constructor = superclass;
    }
}

function extend(subclass, superclass){
    function F() {};
    F.prototype = superclass.prototype;
    subclass.prototype = new F();
    subclass.prototype.constructor = subclass;
    
    
    subclass.superclass = superclass.prototype;
    if (superclass.prototype.constructor == Object.prototype.constructor){
        superclass.prototype.constructor = superclass;
    }
}

function extend(subclass, superclass){

function F() {};

F.prototype = superclass.prototype;

subclass.prototype = new F();

subclass.prototype.constructor = subclass;





subclass.superclass = superclass.prototype;

if (superclass.prototype.constructor == Object.prototype.constructor){

superclass.prototype.constructor = superclass;

}

}