Decode JWT

Gist | Install Decode JWT

jwt.io is too slow to load for me. This is instant!

• Extracts out the token from the entered string and then decodes it.
• Provides live hint of entered string if contains valid token or not.

https://user-images.githubusercontent.com/5556114/116467402-4071ff80-a88d-11eb-86b4-ad58771d7bd6.mov

// Menu: Decode JWT
// Description: Enter any string which contains valid jwt.
// Author: Ravi Sharma
// Twitter: @irvisharma

/** @type typeof import("jsonwebtoken") */
const jwt = await npm('jsonwebtoken');

try {
  const dirtyEncodedToken = await arg('Paste token here', generateLiveHint);
  const decoded = decodeToken(dirtyEncodedToken)

  if (decoded === null) {
    throw 'cannot parse, invalid token'
  }

  showOutput(decoded);
  console.log(decoded);

} catch (e) {
  showError(e)
}

function decodeToken(dirtyEncodedToken){
  try{
    const extractedToken = dirtyEncodedToken.match(/[A-Za-z0-9-_=]+\.[A-Za-z0-9-_=]+\.?[A-Za-z0-9-_.+/=]*/)[0]
    return jwt.decode(extractedToken);
  } catch (e) {
    return null;
  }
}

async function generateLiveHint(userInput){
  const tokenValidHint = decodeToken(userInput) !== null ? '✅ Found valid token' : `❌ Could not parse <br><br> ${userInput}`;
  return md(`
  _Press enter after entering to token show details_
  <br/><br/>
  ${userInput && tokenValidHint}
  `)
}

function showOutput(value) {
  return show(`
<pre style="font-family: Menlo; background: darkslategray; color: navajowhite; font-size: 1.2rem; padding: 1.5em;">
${JSON.stringify(value, null, 2)}
</pre>
`);
}

function showError(e){
  show(`
<h1 style="background: darkslategray; color: white; font-family: Menlo;">Could not decode, Did you entered valid token? <br/><br/> ${e}</h1>
`);
}