CODEWITHSUNDEEP
javascriptinheritance
Kavin Java
Kavin Java

Reputation: 71

How to stop inheriting certain property of parent object in javascript

I want stop inheriting a certain property from the parent object. How can I achieve that through inheritance in Javascript?

Here's an example:

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();

In this example I don't want to inherit the privatenumber property to child.

Upvotes: 0

Views: 1170

Answers (2)

Oriol
Oriol

Reputation: 288600

A simple way is overriding it with undefined:

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

Note that "privatenumber" in obj2 will still return true.

Upvotes: 0

Paul S.
Paul S.

Reputation: 66364

Don't use instances in the prototype chain, inherit directly from the prototype.

If the instance with the inheritance should be constructed by the other constructor too, tell it so

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);

Now look at what we have;

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

Upvotes: 1

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