Constructor of subclass' prototype is enumerable in TypeScript

Question

Here is my code:

class Animal {
    constructor(public name: string){}
}
class Cat extends Animal {
    constructor(public name: string) {
        super(name);
    }
}

It outputs the following code:

var __extends = this.__extends || function (d, b) {
    for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p];
    function __() { this.constructor = d; }
    __.prototype = b.prototype;
    d.prototype = new __();
};
var Animal = (function () {
    function Animal(name) {
        this.name = name;
    }
    return Animal;
})();
var Cat = (function (_super) {
    __extends(Cat, _super);
    function Cat(name) {
        _super.call(this, name);
        this.name = name;
    }
    return Cat;
})(Animal);

And as you can see from this demo , the constructor gets enumerated as a key.

The property constructor of the Class Cat's prototype should be non-enumerable, but the method __extends has changed this. How can I repair this?

I know the following code can achieve this, but I want a way that TypeScript natively supports!

Object.defineProperty(Cat.prototype, 'constructor', {
    enumerable: false
});

Answer 1

You need to define your own __extends variable that uses Object.create instead of new __() to setup the prototype chain.

There is a feature request to allow you to do this at a global level: https://github.com/Microsoft/TypeScript/issues/1622