CODEWITHSUNDEEP
javascript
Julian Lachniet
Julian Lachniet

Reputation: 323

Recreating prompt(); functionality with <input>

I have a sort of a strange problem with the structure of my JS code. It is a convertor from Brainfuck to JavaScript. Then it runs the code it has generated.

With this in mind, I have noticed a problem with the prompt(); command. It seems to, in some situations, show the prompt box before the previous command (changing the DOM) finishes.

My solution is to show an <input type="text"> box, initially set to display:none in CSS. However, I need a way to wait for the input to change. I tried this code:

while (document.getElementById("input") == ""){}

But this freezes the DOM. I need a way to passively wait for any user input, then continue with the script.

Keep in mind, I can't use onkeydown, external functions, etc.

Thanks!

Upvotes: 1

Views: 94

Answers (2)

trincot
trincot

Reputation: 351384

To wait for user input in a non-blocking way, you need to run asynchronous code. This you do by providing a callback function which should be called when a certain event takes place. In your case, this could be when the input value is submitted:

var inp = document.getElementById("inp");

inp.addEventListener('change', function(e) {
  var value = this.value;
  alert('you entered: ' + value);
  // all code that needs the value, should come here,
  // or should be called from here.
});
Exit field to submit value:
<input id="inp">

Upvotes: 1

Yangshun Tay
Yangshun Tay

Reputation: 53229

There's no way to stop script execution besides using native functions like alert, confirm, prompt.

Try wrapping your prompt inside a setTimeout. Start with a value of 0 to see if it works.

setTimeout(function () {
  prompt('your prompt');
}, 0);

Using setTimeout with a value of 0 pushes the execution of the prompt to the back of the event loop, and may possibly run after your DOM updates.

Read more about this technique here: https://www.quora.com/What-does-setTimeout-with-a-0ms-delay-do

Upvotes: 1

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