instanceof operator doesn't work properly since 2.1.4

[dvabuzyarov]

TypeScript Version: 2.1.5

Code

export class HttpError extends Error {
    constructor() {
        super();
    }
}

export class HttpLoginError extends HttpError {
    constructor() {
        super();
    }
}

const error = new HttpLoginError();

Expected behavior:
(error instanceof HttpLoginError); //returns true
(error instanceof HttpError); //returns true
(error instanceof Error); //returns true

Actual behavior:
(error instanceof HttpLoginError); //returns false
(error instanceof HttpError); //returns false
(error instanceof Error); //returns true

[DanielRosenwasser]

This was an intentional change in 2.2 (see #12123 and the section on our wiki), but is difficult to overcome through compilation. I believe there's some conversation in #12790 for workarounds.

A workaround you can take now is create an intermediate class that you can extend from.

export interface MyErrorStatic {
    new (message?: string): RxError;
}
export interface MyError extends Error {}

export const MyError: MyErrorStatic = function MyError(this: Error, message: string) {
    const err = Error.call(this, message);
    this.message = message;
    this.stack = err.stack;
    return err;
} as any;

export class HttpError extends MyError {
    // ...
}

In TypeScript 2.2, you'll be able to set the prototype on your own.

// Use this class to correct the prototype chain.
export class MyError extends Error {
    __proto__: Error;
    constructor(message?: string) {
        const trueProto = new.target.prototype;
        super(message);

        // Alternatively use Object.setPrototypeOf if you have an ES6 environment.
        this.__proto__ = trueProto;
    }
}

[jimmykane]

Sorry but I am having a similar issue with latest Typescript can you check the following @DanielRosenwasser

I construct the following

as you can see that Data I have is an instance of Altitude but they only refer to number

on a second page reload this changes and becomes vise versa