document.querySelector('#go').onclick = function () {

  id = Number(document.querySelector("#in").value);

  document.querySelector("#out").innerHTML = ID2Key(id,7684512);

}

​

function ID2Key(id, secret) {

    var table = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';

    var key = new Array(5); // Initialize the key

​

    var scrambled = id ^ secret; // "Encrypt" the employee ID with a secret

​

    var capital_index = scrambled % 2; // Determine if the Capital letter should be first

    scrambled = (scrambled - capital_index) / 2;

    var capital = table[36 + (scrambled % 26)]; // Find the capital letter

    key[capital_index] = capital;

    scrambled = (scrambled - (scrambled % 26)) / 26;

​

    var num = scrambled % 10; // Find the number

    key[1-capital_index] = table[num]; // If the capital letter is first place the number second and visa versa

    scrambled = (scrambled - (scrambled % 10)) / 10;

​

    // Find the remaining 3 characters

    key[2] = table[scrambled % 62];

    scrambled = (scrambled - (scrambled % 62)) / 62;

​

    key[3] = table[scrambled % 62];

    scrambled = (scrambled - (scrambled % 62)) / 62;

​

    key[4] = table[scrambled % 62];

    return key.join("");

}