用循环替换条件语句

Question

I am trying to make a guessing game that generates a random number which the user guesses. This guessing game must use some kind of loop. Right now it is enclosed in a function that is called when the user clicks a button, and a boolean that limits the number of guesses the user can make.

To my understanding, a loop runs without stopping until its conditions have been satisfied. If I were to have a loop in this situation, the final output would be the loop's last iteration. NumGuesses would have a value of 6 because that was when the loop stopped. How can I replace the conditional with a loop and still have it work?

//Declare variables and constants 
var guessesLeft;                               //number of guesses the user has left
var userGuess;                                //user's guess
var highLimit = 1000;                         //high parameter
var numGuesses = 1;                           //number of guesess the user has guessed
var allowedGuesses = 6;                      //number of allowed guesses
var NL = "\n";                               //new line

    //function to be called when the user presses Submit Guess
    function guessingGame() { 
        //random number that is generated
        var randNum = Math.floor(Math.random() * highLimit + 1); 
        if (numGuesses <= allowedGuesses) { 
        userGuess = prompt("Enter a number between 1 and " + highLimit + ": " , "")
        userGuess = parseInt(userGuess);
        guessesLeft = (allowedGuesses - numGuesses) + " guesses left.";
            //If userGuess is in the specified parameters
            //If userGuess is larger than 1 and smaller than the higher parameter
            if ((userGuess > 1) && (userGuess < highLimit)) {

                //If userGuess does not equal randNum
                if (userGuess !== randNum) {

                    //If userGuess is too low
                    if (userGuess < randNum) {
                        //output 
                        document.numForm.gameResults.value = "You guessed too low! Please guess again. " + NL + "Your current number of guesses: " + numGuesses + NL + "You have " + guessesLeft;
                    }
                    //If userGuess is too high
                    else if (userGuess > randNum) {
                        document.numForm.gameResults.value = "You guessed too high! Please guess again. " + NL + "Your current number of guesses: " + numGuesses + NL + "You have " + guessesLeft;
                    }//end if                      
                }
                else {
                    //If userGuess is correct
                    document.numForm.gameResults.value = "You guessed correctly!";
                }//end if
            }

            else {
                document.numForm.gameResults.value =  "Your guess was out of the specified parameters. Please try again. " + NL + "Your current number of guesses: " + numGuesses + NL + "You currently have " + guessesLeft;
                    //user may have entered their guess wrong
                    numGuesses--;
            }//end if 
            //add to number of guesses so the program stops when it reaches the allowed number
            numGuesses++;
        }//end outer if statement
        return false;
    }//end guessingGame()

Answer 1

It sounds like the problem statement expects you to block waiting for user input as opposed to triggering a function in response to a DOM event.

Have a look at window.prompt

Placing this in a loop would block the loop until the user responded.

Answer 2

Using prompt() as suggested by retrohacker and a do {} while () loop, the following code demonstrates this in action:

 var minNumber = 1; var maxNumber = 2; var guessesLeft = 3; var numberToBeGuessed = minNumber + (Math.random() * (maxNumber - minNumber + 1) | 0); var succeeded; var message = 'Make a guess'; do { if (prompt(message) == numberToBeGuessed) { alert('Correct, the number is ' + numberToBeGuessed); succeeded = true; } else { guessesLeft--; message = 'Try again, ' + guessesLeft + ' guess' + (guessesLeft > 1 ? 'es' : '') + ' left'; } } while (!succeeded && guessesLeft)