create a string of random characters with a maximum of 12 characters

Script
function createRandomString() {
  var randomString = '';
  var possible = 'abcdefghijklmnopqrstuvwxyz0123456789';
  for (var i = 0; i < 12; i++)
    randomString += possible.charAt(Math.floor(Math.random() * possible.length));
  return randomString;
}
    
console.log(createRandomString())