How to decode the JWT encoded token payload on client-side in angular?

Question

I am getting one JWT encoded access token from my API in response. But I am not able to decode it and get it in JSON format. I tried using the angular2-jwt library for it, but it did not worked. I am writing my code below:

 setXAuthorizationToken(client){
    let requestHeader = new Headers();
    requestHeader.append('Content-Type', 'application/x-www-form-urlencoded');
    this.http.post(client.clientURL + "oauth/token", 'grant_type=password&client_id=toto&client_secret=sec&' +  'username=' + client.username
    + '&password=' + client.password, {
      headers: requestHeader
    }).map(res=>res.json())
    .subscribe((token) =>{
      if(!token.access_token){
          return;
      }
      else{
       var decompressToken = LZString.decompressFromEncodedURIComponent(token.access_token);
       console.log(decompressToken);
}
    });
    }

Can anybody please help me solve this issue?

Answer 1

I use Auth0's jwt-decode package for decoding JWT token in Angular; this package works for me fine.

After installing the package through this command:

npm install jwt-decode

Import this package into your TypeScript class using this syntax:

import * as jwt_decode from "jwt-decode";

Or for newer versions (3 and above):

import jwt_decode from 'jwt-decode';

Then use this library method for decoding your access token like this:

getDecodedAccessToken(token: string): any {
  try {
    return jwt_decode(token);
  } catch(Error) {
    return null;
  }
}

The token parameter defines your access token which comes from your API.

The jwt_decode method returns the decoded token info as an object; you can access any info from your token.

Example

const tokenInfo = this.getDecodedAccessToken(token); // decode token
const expireDate = tokenInfo.exp; // get token expiration dateTime
console.log(tokenInfo); // show decoded token object in console

jwt-decode is a small browser library that helps to decode JWTs token which is Base64Url encoded.

IMPORTANT: This library doesn't validate the token, any well formed JWT can be decoded. You should validate the token in your server-side logic by using something like express-jwt, koa-jwt, Owin Bearer JWT, etc.

Answer 2

Try and use the JavaScript build in function atob(). Kind of like this:

atob(token.split('.')[1])

Notes:

• The token is actually a string.

• If you want to know why i split the token you should check this website jwt.io.

Answer 3

Use @auth0/angular-jwt

Step - 1 : Install using npm

npm install @auth0/angular-jwt

Step - 2 : Import the package

import { JwtHelperService } from '@auth0/angular-jwt';

Step - 3 : Create an instance and use

const helper = new JwtHelperService();

const decodedToken = helper.decodeToken(myRawToken);

// Other functions
const expirationDate = helper.getTokenExpirationDate(myRawToken);
const isExpired = helper.isTokenExpired(myRawToken);