JavaScript 4种继承方式

//1.对象冒充

function ClassA(sColor) {
    this.color = sColor;
    this.sayColor = function() {
        alert(this.color);
    };
}

function ClassB(sColor) {
    this.newMethod = ClassA;
    this.newMethod(sColor);
    delete this.newMethod;
}

var objA = new ClassA("red");
var objB = new ClassB("blue");
objA.sayColor();
objB.sayColor();

// 2.Call()方法

function ClassA(sColor) {
    this.color = sColor;
    this.sayColor = function() {
        alert(this.color);
    };
}

function ClassB(sColor) {
    ClassA.call(this, sColor);
}

var objB = new ClassB("yellow");
var objA = new ClassA("red");
objA.sayColor();
objB.sayColor();

// 3. apply()方法

function ClassA(sColor) {
    this.color = sColor;
    this.sayColor = function() {
        alert(this.color);
    };
}

function ClassB(sColor) {
    ClassA.apply(this, arguments);
}

var objB = new ClassB("black");
objB.sayColor();

// 4. 原型链

function ClassA() {
}

ClassA.prototype.color = "red";
ClassA.prototype.sayColor = function() {
    alert(this.color);
};

function ClassB() {
}

ClassB.prototype = new ClassA();

var objA = new ClassA();
var objB = new ClassB();
objB.color = "green";
objB.sayColor();