How to decode a jwt token in JavaScript

In this Article we will go through how to decode a jwt token only using single line of code in JavaScript. This is a one-line JavaScript code snippet that uses one of the most popular ES6 features => Arrow Function.

Let's define this short function:

const decode = token => decodeURIComponent(atob(token.split('.')[1].replace('-', '+').replace('_', '/')).split('').map(c => `%${('00' + c.charCodeAt(0).toString(16)).slice(-2)}`).join(''));

decode(`
    eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.
    eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0I
    joxNTE2MjM5MDIyfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c
`);

// { "sub": "1234567890", "name": "John Doe", "iat": 1516239022 }