TypeScript must-know

TYPESCRIPT.md

Questions

TypeScript and built-in error-checks

Stack Overflow

• Implementing instanceof checks for custom typescript Error instances?](https://stackoverflow.com/questions/55065742/implementing-instanceof-checks-for-custom-typescript-error-instances)

Solutions

Read https://github.com/Microsoft/TypeScript/wiki/Breaking-Changes#extending-built-ins-like-error-array-and-map-may-no-longer-work

Now, a complete implementation of @Mathyn and @TmTron answers:

/**
 * Base Error.
 */
class BaseError extends Error {
  constructor(message?: string) {
    const trueProto = new.target.prototype;
    super(message);
    Object.setPrototypeOf(this, trueProto);
  }
}

class Err1 extends BaseError {}
const e1 = new Err1();
console.log(e1 instanceof Err1); // true
console.log(e1 instanceof Error); // true

class Err2 extends Err1 {}
const e2 = new Err2();
console.log(e2 instanceof Err1); // true
console.log(e2 instanceof Err2); // true
console.log(e2 instanceof Error); // true

class NoBaseErr extends Error {}
const x = new NoBaseErr();
console.log(x instanceof Error); // true
console.log(x instanceof NoBaseErr); // false !!!

Package

import BaseError from 'ts-base-error';

See: https://www.npmjs.com/package/ts-base-error