do while javascript - loop for guessing game

Question

<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN">
<html> 
<head>
<title>Game</title>
<script type="text/javascript" src="game.js"></script>

</head>
<body>
    <h1>GameSite</h1>
    <p> This program will generate a random number. Please input your guess in the box!</p>
    <button onclick="guessGame()">Press me to play a quick game!</button>

<script>
    function guessGame(){
        number = Math.floor(Math.random()*11);
        document.write(number);
        var guess = prompt("Guess a number: ");
            do {
                guess = prompt("Keep guessing!");
                if (number < guess) {
                    prompt("You've guessed too high!");
                } else if (number > guess) {
                    prompt("You've guessed too low!");
                } else document.write("Good Job!");
            } while (guess != number);
    }
    </script>
    </body> 
</html>

I am having trouble with the loop. It loops fine but if I move the guess statement too after the if statement it goes back to that each time. If I put it outside the if statement then it seems to not actually allow me to guess a valid number. It's hard to explain :\

Nina Scholz · Accepted Answer · 2015-07-31T10:32:09.210

5

I would suggest just to use only one prompt and assign it to the variable.

function guessGame() {
    var number = Math.random() * 11 | 0,
        guess,
        text = 'Guess a number:';
    do {
        guess = prompt(text);
        if (number < guess) {
            text = "You've guessed too high!";
        } else if (number > guess) {
            text = "You've guessed too low!";
        }
    } while (guess != number);
    document.write("Good Job!");
}
guessGame();

edited Jul 31 '15 at 10:32

answered Jul 31 '15 at 08:26

Nina Scholz

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But the correct number appears as you press the button. – Altay Mazlum Jul 31 '15 at 09:19
@AltayMazlum, this behaviour is in the original code as well. – Nina Scholz Jul 31 '15 at 09:37
I know that but you answer and don't fix it, why? – Altay Mazlum Jul 31 '15 at 09:38
@AltayMazlum, is this better? – Nina Scholz Jul 31 '15 at 10:34
Yes, thank you. I was asking because I wanted to know how it's done too. – Altay Mazlum Jul 31 '15 at 10:40

eddyjs · Answer 2 · 2015-07-31T08:48:47.360

1

Try this:

function guessGame(){
    number = Math.floor(Math.random()*11);
    document.write(number);
    var guess = prompt("Guess a number: ");
    while (guess != number) {
        if (number < guess) {
            guess = prompt("You've guessed too high! Keep guessing!");
        } else {
            guess = prompt("You've guessed too low! Keep guessing!");
        }
    }
    document.write("Good Job!");   
}

The while loop will keep running until the correct number is guessed, and then it will terminate.

edit: sorry, mistakes from typing too fast

edited Jul 31 '15 at 08:48

answered Jul 31 '15 at 08:23

eddyjs

1,270
10
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1

The `!==` operator is really nasty joke from your side: since prompt result is string and number is integer, the user will be doomed to guess forever. – Jan Turoň Jul 31 '15 at 08:48
Oh thanks for that correction Jan, I'm so used to just always using !== that I glazed over that. – eddyjs Jul 31 '15 at 08:49
Why did you remove it? I would keep it, so the game would be much more fun >:-D – Jan Turoň Jul 31 '15 at 08:49

score 0 · Answer 3 · answered Jul 31 '15 at 08:42

I'd recommend use alert when you don't need user's response

function guessGame(){
    number = Math.floor(Math.random()*11);
    var guess;
        do {
            guess = prompt("Guess a number: "); // you should handle string input here
            if (number < guess) {
                alert("You've guessed too high!");
                alert("Keep guessing!");
            } else if (number > guess) {
                alert("You've guessed too low!");
                alert("Keep guessing!");
            } 
        } while (guess != number);
        alert("Good Job!");
}

Thanks! I ended up using an alert to follow the style of the pop up boxes! — Kacey Gambill, Jul 31 '15 at 13:57

score 0 · Answer 4 · answered Jul 31 '15 at 09:00

Trust me, I'm a programmer.

    function guessGame() {
    guess:
            var number = Math.floor(Math.random() * 11);
            document.write(number);
            var guess;// = prompt("Guess a number: ");
            var text = 'Guess a number:';
            guess = prompt(text);
            if (number == guess) {
                document.write("Good Job!");
                return true;
            } else {
            if (number < guess) {
                text = "You've guessed too low!";
            } else {
                text = "You've guessed too high!";
            }
                goto guess;
            }
}
        guessGame();

using goto in JS is [not that easy](http://stackoverflow.com/a/9751229/343721), but on the other hand we must get rid of the social bandwagon of goto haters. — Jan Turoň, Jul 31 '15 at 14:26

do while javascript - loop for guessing game

4 Answers4