@es-labs/node/web/parse-jwt.js

Reusable library

// parses and returns JWT payload
// exceptions to be handled by caller
/**
 * 
 * @param {string} token 
 * @returns 
 */
export default function (token) {
  const base64Url = token.split('.')[1]
  const base64 = base64Url.replace(/-/g, '+').replace(/_/g, '/')
  const jsonPayload = decodeURIComponent(atob(base64).split('').map(function(c) {
    return '%' + ('00' + c.charCodeAt(0).toString(16)).slice(-2)
  }).join(''))
  return JSON.parse(jsonPayload)
}