Unable to check if thrown error is an instance of a custom error class-CodePudding

I have created a custom error class which extends the built-in Error class and adds a new value to it. The error itself works as expected.

I want to handle this error explicitly when I catch it.

This is my custom error class:

export default class CustomHttpError extends Error {
  constructor(readonly httpCode: number, readonly message: string) {
    super(message);

    this.name = 'CustomHttpError';
  }
}

This is how I am trying to test it:

const CustomHttpError = require('./lib/src/errors/CustomHttpError');

try {
  throw new CustomHttpError(420, 'Enhance Your Calm');
} catch (e) {
  if (e instanceof CustomHttpError) {
    console.log(CustomHttpError.httpCode);
  }
}

I receive this error:

  if (e instanceof CustomHttpError) {
        ^

TypeError: Right-hand side of 'instanceof' is not callable

CodePudding user response：

Assuming that you're using TypeScript in the main module, instead of require, you probably want to do

import CustomHttpError from './lib/src/errors/CustomHttpError';

Although you could do

const CustomHttpError = require('./lib/src/errors/CustomHttpError').default;

This is happening based on your tsconfig.json's esModuleInterop setting. You can read more about it here.