How to import TokenExpiredError thrown by jsonwebtoken's verify?

Issue

I'd like to check whether the type of an Error is TokenExpiredError throws by the jwt.verify function of the jsonwebtoken library using Typescript's instanceof, e.g.

import jwt from "jsonwebtoken";

function someFunction() {
    try {
        return jwt.verify(token, key);
    }catch(err) {
        if(err instanceof TokenExpiredError) {
            return attemptRenewal()
        }
        throw err
    }
}

How can I import the symbol TokenExpiredError?

I don't find any documentation about this important class and the only intuitive that comes to my mind

import { jwt, TokenExpiredError } from "jsonwebtoken";

causes jwt to be undefined.

I'm aware of workaround like performing string comparison with the class name, but I'd like to produce clean code.

I'm using jsonwebtoken 8.5.1.

Solution

jsonwebtoken export a default object like: source

module.exports = {
  decode: require('./decode'),
  verify: require('./verify'),
  sign: require('./sign'),
  JsonWebTokenError: require('./lib/JsonWebTokenError'),
  NotBeforeError: require('./lib/NotBeforeError'),
  TokenExpiredError: require('./lib/TokenExpiredError'),
};

This mean, when you use import jwt from "jsonwebtoken"; syntax, jwt will come to a object with all properties of default export.

You can not use import { jwt, TokenExpiredError } from "jsonwebtoken";, because in default export object, we do not have jwt property,

If you want to import TokenExpiredError and the default object, you can follow a syntax like: import jwt, {TokenExpiredError} from "jsonwebtoken"; , then jwt still is default export object, and you have TokenExpiredError object (jwt.TokenExpiredError and TokenExpiredError is the same).

If you just want to use verify function and TokenExpiredError, the import line will come to: import {TokenExpiredError, verify} from "jsonwebtoken";, then you function will be like:

import {TokenExpiredError, verify} from "jsonwebtoken";

function someFunction() {
  try {
    return verify(token, key);
  } catch (err) {
    if (err instanceof TokenExpiredError) {
      return attemptRenewal()
    }
    throw err
  }
}

Answered By - hoangdv