如何在javascript

Question

我想停止从父对象继承某个属性。如何通过Javascript中的继承实现这一目标？

以下是一个例子：

var fun1 = function () {
    this.name = "xxx";
    this.privatenumber = 98765432100;
}
fun1.prototype.f = "yyy";
var obj1 = new fun1();
var fun2 = function () {}
fun2.prototype = Object.create(obj1);
var obj2 = new fun2();

在此示例中，我不想将privatenumber属性继承到子级。

Answer 1

不要在原型链中使用实例，直接从原型继承。

如果具有继承的实例也应该由其他构造函数构造，那么告诉它

function Fun1() {
    this.name = "xxx";
    this.privatenumber = 98765432100;
}
Fun1.prototype.f = "yyy";

function Fun2() {
    // if instances of Fun2 should be constructed by Fun1 then
    Fun1.call(this);
    // and if you still don't want `privatenumber` which is now an own property, delete it
    delete this.privatenumber;
}
Fun2.prototype = Object.create(Fun1.prototype);

现在看看我们有什么;

var foo = new Fun2(); // Fun2 own `{name: "xxx"}`, inherting `{f: "yyy"}`
'privatenumber' in foo; // false

Answer 2

一种简单的方法是用undefined覆盖它：

fun2.prototype = Object.create(obj1);
fun2.prototype.privatenumber = undefined;
var obj2 = new fun2();
obj2.privatenumber; // undefined

请注意，"privatenumber" in obj2仍会返回true。