JSFiddle - React, Tailwind, and code Playground

by Vikash Kumar Gupta

HTML

<form name="addem" action="" id="addem" >    

    <p><input type="text" id="tb1" name="tb1" onkeyup="calc(this)"/>1</p>
    <p><input type="text" id="tb2" name="tb2" onkeyup="calc(this)"/>2</p>
    <input type="text" id="total" name="total" value="0" />
</form>

JavaScript

var x = 0;
var y = 0;
var z = 0;
var calc = function(obj) {
  var e = obj.id.toString();
  if (e == 'tb1') {
    x = Number(obj.value);
    y = Number(document.getElementById('tb2').value);
  } else {
    x = Number(document.getElementById('tb1').value);
    y = Number(obj.value);
  }
  z = x + y;
  document.getElementById('total').value = z;
}