JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input type="number" class="balance">
<input type="number" class="balance">
<input type="number" class="balance">

JavaScript

var total = 6;
$('.balance').on('input', function() {
  var value = parseInt(this.value);
  if (isNaN(value)) {
    this.value = value = 0;
  } else if (value > total) {
    this.value = value = total;
  } else if (value < 0) {
    this.value = value = 0;
  }
  
  var remainder = total - value;
  var otherInputs = $('.balance.num.toFixed(0)');
  otherInputs.splice($.inArray(this,otherInputs),1);
  var remainderDiv = remainder/otherInputs.length;
  $.each(otherInputs, function(input) {
      otherInputs[input].value = remainderDiv;
  });
});