How to use a while loop to prompt user until they enter 1 of 4 inputs-CodePudding

I'm stuck on how to get this while loop to function properly. I want the program to prompt the user with a question 'Rock, paper, or scissors?' to which they can correctly enter 'rock', 'paper', 'scissors', or 'bomb' (cheat code for auto-win... lol). If they type in anything other than those 4 acceptable inputs, an alert should appear. Then they should be prompted with the same question again. This should repeat until they enter one of those 4 acceptable inputs.

So far, it works if they type in their choice correctly the first time the prompt appears. However, if they type something other than the above 4 acceptable inputs, triggering the alert and the prompt in the while loop, the program does not run correctly even if they enter one of the 4 inputs the next time they are prompted. It gets stuck alternating between the alert and the prompt for eternity.

So how can I get this while loop to work?

function playGame () {
    var input = prompt ('Rock, paper, or scissors?').toLowerCase();
    // testing 123
    // console.log (input);
    var jkl = 0;
    if (input === 'rock' || input === 'paper' || input === 'scissors' || input === 'bomb') {
        jkl  
    };
    while (jkl === 0) {
        alert ('ErRoR eRrOr 3rR0r!!!!11');
        prompt ('Rock, paper, or scissors?').toLowerCase();
        if (input === 'rock' || input === 'paper' || input === 'scissors' || input === 'bomb') {
            jkl  
        };
    }
    console.log (input);
    var userChoice = getUserChoice (input);
    var computerChoice = getComputerChoice ();
    console.log (`You: ${userChoice}`);
    console.log (`Computer: ${computerChoice}`);
    console.log (determineWinner (userChoice, computerChoice));
};

playGame ();

After the attempted while loop there is more code that pertains to functions appearing earlier in the program. Ignore that I suppose. Unless anyone thinks it's relevant, in which case I can post that too. Just didn't want to paste a massive wall of code in here.

CodePudding user response：

You can change this line

prompt ('Rock, paper, or scissors?').toLowerCase();

input = prompt ('Rock, paper, or scissors?').toLowerCase();

Your code is checking the input variable without updating it.

CodePudding user response：

You need to update the input variable in the loop.

const options = ['rock', 'paper', 'scissors', 'bomb']
const getOptionPrompt = () => prompt('Rock, paper, or scissors?').toLowerCase();
const checkOption = (input, options) => options.includes(input)

function playGame() {
  let input = getOptionPrompt();
  // testing 123
  // console.log (input);
  var jkl = 0;
  if (checkOption(input, options)) {
    jkl  
  };
  while (jkl === 0) {
    alert('ErRoR eRrOr 3rR0r!!!!11');
    input = getOptionPrompt();
    if (checkOption(input, options)) {
      jkl  
    };
  }
  console.log(input);
  // the functions after this are not defined in the example
  /*
  var userChoice = getUserChoice(input);
  var computerChoice = getComputerChoice();
  console.log(`You: ${userChoice}`);
  console.log(`Computer: ${computerChoice}`);
  console.log(determineWinner(userChoice, computerChoice));
  */
};

playGame();

But I would definitely update the logic a bit:

const options = ['rock', 'paper', 'scissors', 'bomb']
const getOptionPrompt = () => prompt('Rock, paper, or scissors?')?.toLowerCase() || null;
const checkOption = (input, options) => options.includes(input)

function playGame(options) {
  const input = getOptionPrompt();

  if (!checkOption(input, options) && input != null) {
    alert('ErRoR eRrOr 3rR0r!!!!11');
    playGame(options)
  } else if (input == null) {
    console.log("game canceled")
  } else {
    console.log("result:", input)
  }
};

playGame(options);

This way you don't need the jkl variable, no need for the while loop - if an answer is typed in that is not acceptable, then an error alert shows & the game starts anew.