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

Posted by Conner Wells
Conner Wells
5,979 Points

What am I supposed to put in the do loop in order for this to work?

I thought I could just state the "secret" variable in order for the variable to be added, but I keep getting the error that the variable has to be defined outside of the loop, but I'm also getting an error that says that the prompt() function must be used inside the loop. I'm really lost and confused.

script.js 
var secret = prompt("What is the secret password?");

do {
  secret;
}

while ( secret !== "sesame" ) {
  document.write("You know the secret password. Welcome.");
}
index.html 
<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>JavaScript Loops</title>
</head>
<body>
<script src="script.js"></script>
</body>
</html>
Justyna Szofinska
Justyna Szofinska
6,178 Points
Justyna Szofinska
Justyna Szofinska
6,178 Points 
var start = false;
var answer = "sesame"; 

do {
  var secret = prompt("What is the secret password?");

  if (secret!==answer) {
    secret;
    start; 
  } else {
    start= true; 
  }

} while (start === false);

I did it this way. It seems to me, that your code doesn't work, because you didn't clearly say what the program should do when the answer is correct or uncorrect.

1 Answer

Gergely Bocz
Gergely Bocz
14,244 Points
Gergely Bocz
Gergely Bocz
14,244 Points

Hi Conner!

First here is a quick summary of the do-while loop: The do-while loop first executes the code inside do, no matter what. Then checks the condition inside while, and based on the condition's return value, it can do 2 things. If the condition is true, then we execute the code inside do again. If the condition is false, then we leave the do-while loop. Essentially it is a while loop that executes at least once.

Please check out the syntax for do-while loops either in the video or here for example, because you didn't write a do-while loop, you wrote something like a do loop - that doesn't exist! - followed by a while loop.

So all we want to do is rewrite our while loop into a do-while loop. Since the code inside do gets called no matter what, we want to write something inside, that can get called, no matter what. This is the reason for your errors. If you define a variable (secret) with a function call to it (prompt), then that function will be called immediately! In short, prompt gets called before we enter the loop, and there is no need for that, just declare the variable without any assignment. But we want to keep on calling prompt as long as the given password is incorrect, so we put it inside the loop. Basically we want to declare the secret variable without assignment because of the do part of the loop, and we want to call prompt every time, the password is not sesame, so we put that inside the loop. Hope it makes sense!

If you want to see how your code behaves with

var secret = prompt("What is the secret password?");

just open the dev tools console and paste your code there and try writing the correct password, "sesame" in there, and see for yourself, that it won't work the first time, you'll have to write it again!

Try to rewrite your code and find the solution yourself, if you need further help just ask for it, and i'll try to help the best i can!