Extend native JavaScript array

Question

Is there any way to inherit a class from JS native function?

For example, I have a JS function like this:

function Xarray()
{
    Array.apply(this, a         


        

Answer 1

Starting in TypeScript 1.6, you can extend the Array type, see What's new in TypeScript

Here's an example:

class MyNewArray extends Array {
    getFirst() {
        return this[0];
    }
}

var myArray = new MyNewArray();
myArray.push("First Element");
console.log(myArray.getFirst()); // "First Element"

If you are emitting to ES5 or below, then use the following code:

class MyNewArray extends Array {
    constructor(...items: T[]) {
        super(...items);
        Object.setPrototypeOf(this, MyNewArray.prototype);
    }

    getFirst() {
        return this[0];
    }
}

Read more about why this is necessary here.