From http://www.html-js.com/article/JavaScript-mode-in-JavaScript-class-inheritance-mode

new_gist_file.js

function Parent(name, age) {
    this.init.apply(this, arguments);
}

Parent.prototype = {
    // 通过init解决参数传递的问题
    init: function (name, age) {
        this.name = name;
        this.age = age;
    },
    say: function () {
        alert('Hi, 我是' + this.name + ", 我今年" + this.age + "岁。")    
    }
}

// 继承辅助函数
var inherit = function () {
    var F = function () {};
    return function (C, P) {
        F.prototype = P.prototype;
        C.prototype = new F();
        C.prototype.constructor = C; // 注意constructor设置为子类的构造函数
        C.parentClass = P.prototype; // 方便调用父对象中的方法
    };
}

function Child(a, b) {
    this.init.apply(this, arguments); 
}
inherit(Child, Parent);

var child0 = new Child('test', '19');
child.say(); // Hi,我是test，我今年19岁
child.prototype.say = function () {
    alert("error...");
};

var child1 = new Child('test2', '20');
child.say(); // Hi,我是test2，我今年20岁