Pausing Javascript execution until button press

Question

I'm creating a visualization of a Sudoku creator for my Algorithms class (in Javascript). The algorithm works great, but I'm having trouble finding a way to pause execution.

Currently, I'm using prompt() to pause, but that's bulky and annoying. Is there any way to pause until another function is run (via HTML button) other than a continuous while loop?

I can post code, but I don't think it's needed. I'm not currently using jQuery, but I can if needed.

no, because window.stop() doesn't stop script execution, it stops window from loading, similar to browser's stop button. — keune
– keune, Commented Apr 28, 2012 at 18:39

gdoron · Accepted Answer · 2012-04-28 18:53:06Z

13

var flag = true;
function foo(){
    if (flag){
        // Do your magic here
        ...
        ...
        setTimeout(foo, 100);
    }
}

function stop(){
    flag = false;
}
<input type="button" onclick="stop();" value="stop it!!!" />

Live DEMO

edited Apr 28, 2012 at 18:53

answered Apr 28, 2012 at 18:34

gdoron

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2 Comments

SomeKittens Over a year ago

I'm trying to avoid having a 'while()' loop cranking along in the background. Is there any other way? (If not, this looks pretty good)

user1233508 Over a year ago

You mean setTimeout(foo), not setTimeout(flag).

Liran H · Accepted Answer · 2017-12-16 00:22:33Z

If what you are trying to pause is a function which would otherwise keep looping, I've come up with a good solution:

HTML

<div id="stuff">Doing stuff</div>
<button id="pause">Pause/Resume</button>

JS

var paused = false;

document.getElementById('pause').addEventListener('click', function() {
  paused = !paused;
  if (!paused) {
    next();
  }
});

function doStuff() {
  // Do whatever you want here, then invoke next() for the next iteration of that function, for example:
  // (Note that the window.setTimeout is NOT part of the solution)
  window.setTimeout(function() {
    document.getElementById('stuff').append('.');
    next();
  }, 300);
}

function next() {
  if (!paused) {
    doStuff();
  }
}

doStuff();

CodePen: https://codepen.io/liranh85/pen/baVqzY?editors=1010

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