Generate a random SHA1 token in browser

randomSHA1.js

// str byteToHex(uint8 byte)
//   converts a single byte to a hex string 
function byteToHex(byte) {
  return ('0' + byte.toString(16)).slice(-2);
}

// str generateId(int len);
//   len - must be an even number (default: 40)
function generateId(len) {
  var arr = new Uint8Array((len || 40) / 2);
  window.crypto.getRandomValues(arr);
  return [].map.call(arr, byteToHex).join("");
}

// Ok, let's check it out!

generateId();
// "1e6ef8d5c851a3b5c5ad78f96dd086e4a77da800"

generateId(20);
// "d2180620d8f781178840"

Original from: https://stackoverflow.com/questions/9407892/how-to-generate-random-sha1-hash-to-use-as-id-in-node-js