JSFiddle - React, Tailwind, and code Playground

HTML

<form>
  Date of dispatch<br>
  <input type="text" name="date_dispatch" id="date_dispatch" value="2016-04-26 10:00:00"><br>
  Expected delivery timne<br>
  <input type="text" name="date_delivery" id="date_delivery">
  <br>
  <input type="submit" value="Submit">
</form>

JavaScript

$(document).ready(function(){

	$('#date_dispatch').change(function() {
  	document.getElementById('date_delivery').value = 'test';
  });

});