Generate random password

gistfile1.js

function generatePassword(length) {
  var charset = "abcdefghijklnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789",
  retVal = "";
  for (var i = 0, n = charset.length; i < length; ++i) {
    retVal += charset.charAt(Math.floor(Math.random() * n));
  }
  return retVal;
}

document.activeElement.value = prompt('Password:', generatePassword(16));