JSFiddle - React, Tailwind, and code Playground

HTML

<input type='text' id='bar'>
<input type='button' id='but' value='Button'>

JavaScript

var a = document.getElementById('but');
znach = 6781222;
a.onclick = function() {
element=document.querySelector('input[id=bar]');
if(!element){
//...
}else{
element.value = znach; 
  var event = new KeyboardEvent('keydown', {
    'view': window,
    'bubbles': true,
    'cancelable': true,
    'which': 13
  });
  element.dispatchEvent(event);
  alert('enter nazhat');
}
}