JSFiddle - React, Tailwind, and code Playground

HTML

FirstBox <input id="first" type="text" name="fname"><br>
 SecondBox <input id="second" type="text" name="lname"><br>
  <button onclick="givevalue()" type="button">Click Me!</button>

JavaScript

givevalue = function(){
console.log("hello")
var value = document.getElementById('first').value;
document.getElementById('second').value = value;

}