Why the IF statement has no condition? "if( correctGuess )" in this loop example?

Question

<script type="text/javascript">
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;
}
while (guessCount <= 10) { 
  guess = prompt('I am thinking of a number between 1 and 10. What is it?');
  guessCount += 1;
  if (parseInt(guess) === randomNumber) {
    correctGuess = true;
    break;
  }  
} 
if( correctGuess ){               // why there's no other conditions.
  document.write('<h1>You guessed the number!</h1>');
  document.write('It took you ' + guessCount + ' tries to guess the number ' + randomNumber);
} else{
  document.write('<h1>Sorry Wrong!</h1>');
}
</script>

Jake Lundberg · Accepted Answer

If statements actually only take one parameter...a boolean (true or false) value. In many cases, you are going to be using conditional operators to compare two or more things, like this: 
javascript
if(a > b) {...}

but even though you have 2 operands, and 1 operator, this actually just equates out to a true or false value, and that is what is passed to the if statement. 
so if a = 1 and b = 2, this statement would obviously be false, so it would be the same as passing: 
javascript
if( false ) {...}

because of this functionality, you don't have to actually compare things within the parenthesis of the if statement...in your case, you have already determined if correctGuess is true or false elsewhere in your code, so you can just pass that into the if statement by itself...
Does that make sense? 
I hope this helps!

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Jonathan Martin

Jonathan Martin

Why the IF statement has no condition? "if( correctGuess )" in this loop example?

1 Answer

Jake Lundberg

Jake Lundberg

Jonathan Martin

Jonathan Martin