Custom error class in TypeScript

Question

I'd like to create my own error class in TypeScript, extending core Error to provide better error handling and customized reporting. For example, I want to create an HttpRequestError class with url, response and body passed into its constructor, which reponds with Http request to http://example.com failed with status code 500 and message: Something went wrong and proper stack trace.

How to extend core Error class in TypeScript? I've already found post in SO: How do I extend a host object (e.g. Error) in TypeScript but this solution doesn't work for me. I use TypeScript 1.5.3

Any ideas?

Answer 1

TypeScript 2.1 had a breaking changes regarding Extending built-ins like Error.

From the TypeScript breaking changes documentation

class FooError extends Error {     constructor(msg: string) {         super(msg);          // Set the prototype explicitly.         Object.setPrototypeOf(this, FooError.prototype);     }      sayHello() {         return "hello " + this.message;     } } 

Then you can use:

let error = new FooError("Something really bad went wrong"); if(error instanceof FooError){    console.log(error.sayHello()); } 

Answer 2

Until 1.6 rolls around, I've just been making my own extendable classes.

class BaseError {     constructor () {         Error.apply(this, arguments);     } }  BaseError.prototype = new Error();  class HttpRequestError extends BaseError {     constructor (public status: number, public message: string) {         super();         } }  var error = new HttpRequestError(500, 'Server Error');  console.log(     error,     // True     error instanceof HttpRequestError,     // True     error instanceof Error );