Can Someone Please Explain How The Js Code Works.

var wordLetters    = ['G', 'O', 'A', 'T'];
var guessedLetters  = ['_', '_', '_', '_'];
 
function guessLetter(letter) {
    var goodGuess = false;
    var moreToGuess = false;
    for (var i = 0; i < wordLetters.length; i++) {
        if (wordLetters[i] == letter) {
            guessedLetters[i] = letter;
            goodGuess = true;
        }
        if (guessedLetters[i] == '_') {
            moreToGuess = true;
        }
    }
    if (goodGuess) {
        alert('Yay, you found a letter!');
        document.write(guessedLetters.join(''));
        if (!moreToGuess) {
            alert('YOU WON!');
        }
    } else {
        alert('Oh noes, thats not right!');
    }
}
 
guessLetter('G');
guessLetter('I');
guessLetter('O');
guessLetter('A');
guessLetter('T');

Code (markup):

 

There is a two array that is wordLetters, guessedLetters.

guessLetter is a function.

guessLetter('G'); will call function guessLetter.

Now the for loop will check the latter is available in array "wordLetters" or not
if it will available in array then set goodGuess = true; and set that latter in guessedLetters it will check for whole array "wordLetters".

After that on line 16 it will check for goodGuess if it's true than alert will be display and print guessletters array with space i.e. (' ') on next statement check condition for more to guess if not then display alert "YOU WON!"

same process will done for all other functions.

Hope this is this is enough to explain this js code