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JavaScript JavaScript Loops, Arrays and Objects Simplify Repetitive Tasks with Loops Exiting Loops

Fuad Muhammad
Fuad Muhammad
4,273 Points
Posted by Fuad Muhammad
Fuad Muhammad
4,273 Points

What is mean "(! correctGuess)" on the do..while loop?

Please explain me about the point on the (! correctGuess) on the do...while loop. For example, if we see this code;

var correctGuess = false do { //something if (condition) { correctGuess = true; } } while ( ! correctGuess) <----- Who goal from this statement? Is first correctGuess(=false)? or correctGuess(=true) on the condition?

1 Answer

Tom Lawrence
Tom Lawrence
8,685 Points

a do while loop runs when the stuff inside the while part is true (but always once whatever), The stuff inside the while part is evaluated into a bool for example:

while (1 === 1)

the first thing that happens is the 1 ===1 is evaluated as a bool, 1 is equal to 1, so it is true, so behind the scenes it is converted into:

while(true) so it then runs based on the true bool value, and re-evaluates it each loop till its false (which it wouldnt ever be in this case)

If for example you then had:

while(correctAnswer)

correctAnsweris already a bool, it does it based on its value, if true it runs, otherwise it wont. You could if you wanted also write while(correctAnswer == true) but no need.

! is a NOT operator, it basically flips everything, so if I wrote:

while(!correctAnswer) if correctAnswer was true, correctAnswer would be flipped to false and not run while(!correctAnswer) if correctAnswer was false, correctAnswer would be flipped to true and run

You can think of it as saying "while correct answer is not true",