Xtykutl

I would like to add few methods to primitives.
I have the following file:

string-extension.ts:

interface String {

    isNullOrEmpty(this: string): boolean;

}



String.prototype.isNullOrEmpty = function (this: string): boolean {

    return !this;

};

I have a component which has the following code:

constructor () {

    let a = "asd";

    alert(a.isNullOrEmpty());

}

no import is added at the top.
When I run the client, it crashes on that line.

a.isNullOrEmpty is not a function

When I inspect the code, i see that my string-extension.ts file wasn't included there.
I am very familiar with the concept in C# but im not quite familiar with it in TypeScript, so if you need more info, ill provide.

Thanks.

first, create global .d.ts. file to set up the signature.

global.d.ts.

export {}; // this file needs to be a module

declare global {

  interface String {

        isNullOrEmpty(this: string): boolean;

  }

}

string-extension.ts:

export {}; // this file needs to be a module

String.prototype.isNullOrEmpty = function (this: string): boolean {

    return !this;

};

Now in the main.ts import the extension

 import './string-extension'