javascript - How to start and stop/pause setInterval?

Question

I'm trying to pause and then play a setInterval loop.

After I have stopped the loop, the "start" button in my attempt doesn't seem to work :

input = document.getElementById("input");

function start() {
  add = setInterval("input.value++", 1000);
}
start();

<input type="number" id="input" />
<input type="button" onclick="clearInterval(add)" value="stop" />
<input type="button" onclick="start()" value="start" />

Answer 1

See Working Demo on jsFiddle: http://jsfiddle.net/qHL8Z/3/

$(function() {
  var timer = null,
    interval = 1000,
    value = 0;

  $("#start").click(function() {
    if (timer !== null) return;
    timer = setInterval(function() {
      $("#input").val(++value);
    }, interval);
  });

  $("#stop").click(function() {
    clearInterval(timer);
    timer = null
  });
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<input type="number" id="input" />
<input id="stop" type="button" value="stop" />
<input id="start" type="button" value="start" />