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JavaScript JavaScript Loops, Arrays and Objects Simplify Repetitive Tasks with Loops `do ... while` Loops

Charlotte Junker
Charlotte Junker
10,261 Points
Posted by Charlotte Junker
Charlotte Junker
10,261 Points

Can't find my error

I just can't work out where I'm going wrong... I think I have the same code as Dave but in Workspaces I get an infinite loop that crashes the browser, and in Atom it writes to the document after one guess - even if the guess is wrong. Any guidance much appreciated. Thanks!

var randomNumber = getRandomNumber(10);
var guess;
var guessCount = 0;
var correctGuess = false;

function getRandomNumber( upper ) {
  var num = Math.floor(Math.random() * upper) + 1; 
  return num;
}

do {
  guess = prompt('What number am I thinking of?');
  guessCount += 1;
  if (parseInt(guess) === randomNumber) {
    correctGuess = true;
  }
} 
while ( correctGuess = false )
  document.write('Well done! I was thinking of ' + randomNumber + ' and it took you ' + guessCount + ' to guess it!');

1 Answer

Alexander Davison
Alexander Davison
65,469 Points

Remember, you use one equal sign for variable assigning, and three equal signs for equality. take a look at this:

var randomNumber = getRandomNumber(10);
var guess;
var guessCount = 0;
var correctGuess = false;

function getRandomNumber( upper ) {
  var num = Math.floor(Math.random() * upper) + 1; 
  return num;
}

do {
  guess = prompt('What number am I thinking of?');
  guessCount += 1;
  if (parseInt(guess) === randomNumber) {
    correctGuess = true;
  }
}
while ( correctGuess === false ) // Now this is fixed :)
  document.write('Well done! I was thinking of ' + randomNumber + ' and it took you ' + guessCount + ' to guess it!');

Also, you can reduce code even more by changing correctGuess === false into !correctGuess. This works because if correctGuess was false, !correctGuess (which is the opposite of correctGuess) would be true. This is the final result:

var randomNumber = getRandomNumber(10);
var guess;
var guessCount = 0;
var correctGuess = false;

function getRandomNumber( upper ) {
  var num = Math.floor(Math.random() * upper) + 1; 
  return num;
}

do {
  guess = prompt('What number am I thinking of?');
  guessCount += 1;
  if (parseInt(guess) === randomNumber) {
    correctGuess = true;
  }
} 
while ( !correctGuess ) // Now THIS looks even better! :D
  document.write('Well done! I was thinking of ' + randomNumber + ' and it took you ' + guessCount + ' to guess it!');

Hope this helps! :smile: ~Alex

Charlotte Junker
Charlotte Junker
10,261 Points
Charlotte Junker
Charlotte Junker
10,261 Points

Thanks Alex! Sorry I took so long to get back to you but that works :)

Alexander Davison
Alexander Davison
65,469 Points

No problem :)