angular-jwt/src/angularJwt/services/jwt.js

Library to help you work with JWTs on AngularJS

 angular.module('angular-jwt.jwt', [])
  .service('jwtHelper', function($window) {

    this.urlBase64Decode = function(str) {
      var output = str.replace(/-/g, '+').replace(/_/g, '/');
      switch (output.length % 4) {
        case 0: { break; }
        case 2: { output += '=='; break; }
        case 3: { output += '='; break; }
        default: {
          throw 'Illegal base64url string!';
        }
      }
      return $window.decodeURIComponent(escape($window.atob(output))); //polyfill https://github.com/davidchambers/Base64.js
    };


    this.decodeToken = function(token) {
      var parts = token.split('.');

      if (parts.length !== 3) {
        throw new Error('JWT must have 3 parts');
      }

      var decoded = this.urlBase64Decode(parts[1]);
      if (!decoded) {
        throw new Error('Cannot decode the token');
      }

      return angular.fromJson(decoded);
    };

    this.getTokenExpirationDate = function(token) {
      var decoded = this.decodeToken(token);

      if(typeof decoded.exp === "undefined") {
        return null;
      }

      var d = new Date(0); // The 0 here is the key, which sets the date to the epoch
      d.setUTCSeconds(decoded.exp);

      return d;
    };

    this.isTokenExpired = function(token, offsetSeconds) {
      var d = this.getTokenExpirationDate(token);
      offsetSeconds = offsetSeconds || 0;
      if (d === null) {
        return false;
      }

      // Token expired?
      return !(d.valueOf() > (new Date().valueOf() + (offsetSeconds * 1000)));
    };
  });