React – How to check if JWT is valid before sending a post request?

Question

Here is a solution with jwt-decode library by comparing the exp attributes in the JWT token with current time. (JWT token is simply a Base64 encoded string)

Install jwt-decode (npm install jwt-decode --save)

 let token = localStorage.getItem(TOKEN);
  let decodedToken = jwt_decode(token);
  console.log("Decoded Token", decodedToken);
  let currentDate = new Date();

  // JWT exp is in seconds
  if (decodedToken.exp * 1000 < currentDate.getTime()) {
    console.log("Token expired.");
  } else {
    console.log("Valid token");   
    result = true;
  }

IMPORTANT: jwt-decode 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.

Leave a Comment Cancel reply