JSFiddle - React, Tailwind, and code Playground

HTML

<input class="input" value="0">
<br />
<br />
<br /> <span></span>

JavaScript

var number = 1500;
    var aValue = 300;

    function count(Item) {
      for (var i = 1; i < 3 + 1; i++) {
          var current = aValue;
          Item.val(aValue += 1);
          if (current < number) {
              setTimeout(function () {
                  count(Item)
              }, 0.1);
          } else {
              callback1();
          }
      }
    }

    count($(".input"));

    function callback1() {
        $('span').text('code here should only run when function count is complete');
    }