prompt and change background color in a loop with native javascript

Question

I would like to write a simply Java script (native) program which MUST use a while loop and do the following.

• prompts user to enter a colour -
• Then change the background to that colour.
• keep prompting them to enter colour and keep changing the background colour until user does not enter anything in the prompt at which point the WHILE loop ends.

I have seen lot of variations of this tackled by using functions - but I want to achieve this only using WHILE loop.

Answer 1

You can loop until value of the prompt entered is null. However you won't see the color change until after you leave the loop because the command prompt is blocking.

while (true) {
  var color = prompt("enter color", "red");
  if (color === null) {
    break;
  }
  document.body.style.backgroundColor = color;
}

This "asynchronous" version allows the browser to paint between prompt to another. But no while here.

function prompt_then(then) {
  var color = prompt("enter color", "red");
  if (color === null) {
    return;
  }
  document.body.style.backgroundColor = color;
  window.setTimeout(then, 1);
}

prompt_then(prompt_then);