Variable undefined in Javascript, help to make it correct

Question

I'm coding a basic rock paper scissors game.

the 2 functions are working fine. the issue is the winner variable is always undefined..

I don't know what to do to correct this. I want it to say who won, computer or the human(user).

function game(x, y) {
    var inputC = computerPlay();
    var inputH = humanPlay();
    var winner;

    if (inputH == 'paper' && inputC == 'scissors') {
        console.log('Computer wins with Scissors ');

        if (inputH == 'scissors' && inputC == 'rock') {
            console.log('Computer wins with rock');

            if (inputC == 'paper' && inputH == 'rock') {
                console.log('Computer wins with paper');
            }
        }

        winner = "computer";
    } else if (inputC == 'paper' && inputH == 'scissors') {
        console.log('Human wins with Scissors ');

        if (inputC == 'scissors' && inputH == 'rock') {
            console.log('Human wins with rock');

            if (inputH == 'paper' && inputC == 'rock') {
                console.log('Human wins with paper');
            }
        }
        winner = "human";
    }
    document.getElementById("text1").innerHTML = winner;
    console.log("result is: " + winner + " wins");
}

I'm sure its something minor but my god I'm all out of ideas.

your conditions are badly nested ... the only time winner will be defined is if inputH == 'paper' && inputC == 'scissors' or inputC == 'paper' && inputH == 'scissors' all other combinations will result in winner being undefined ... don't nest if's like that without understanding — Jaromanda X
– Jaromanda X, Commented Jul 20, 2018 at 1:12
thanks for the advice man, totally agree. tbh this was one of my many attempts to get around winner being undefined. if (inputH == 'paper' && inputC == 'scissors') { console.log('Computer wins with Scissors '); winner = "computer"; } else if (inputC == 'paper' && inputH == 'scissors') { console.log('Human wins with Scissors '); winner = "human"; } this is the original look( its goes through all the conditions but I shortened it here to fit) — Nabeel
– Nabeel, Commented Jul 20, 2018 at 15:36

D. Seah · Accepted Answer · 2018-07-20 23:55:15Z

3

would like this

function game() {
    var inputC = computerPlay();
    var inputH = humanPlay();
    var winner = "human";

    if (inputH === inputC) {
       winner = "nobody";
    } else if ((inputH === 'paper' && inputC === 'scissors') ||
        (inputH === 'scissors' && inputC === 'rock') ||
        (inputH === 'rock' && inputC === 'paper')
    ) {
        console.log('Computer wins with ' + inputC);
        winner = "computer";
    } else {
        console.log('Human wins with ' + inputH);
    }

    document.getElementById("text1").innerHTML = winner;
    console.log("result is: " + winner + " wins");
}

edited Jul 20, 2018 at 23:55

answered Jul 20, 2018 at 1:13

D. Seah

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4 Comments

Jaromanda X Over a year ago

not really ... I'd have else if (inputH == inputC) { winner = 'nobody';} then the else where human wins, to be accurate :p

Jaromanda X Over a year ago

that's not a flaw in your logic per se, I mean the original code had the same problem :p

D. Seah Over a year ago

thanks again. I should have caught it at the first place :-)

D. Seah Over a year ago

two equals works too. IMO, It is a good habit to be strict on comparing variables

deerawan · Accepted Answer · 2018-07-20 04:43:35Z

2

it was undefined because it didn't go to either one of condition.

Another alternative answer from me

function game(x, y) {
  var inputC = computerPlay();
  var inputH = humanPlay();

  var isComputerWin = 
    (inputC == 'scissors' && inputH == 'paper') ||
    (inputC == 'rock' && inputH == 'scissors') ||
    (inputC == 'paper' && inputH == 'rock');

  var winner = isComputerWin ? 'computer' : 'human';
  var winnerWith = isComputerWin ? inputC : inputH;
  console.log(winner + " wins with " + winnerWith);

  document.getElementById("text1").innerHTML = winner;  
  console.log("result is: " + winner + " wins");
}

answered Jul 20, 2018 at 4:43

deerawan

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