JSFiddle - React, Tailwind, and code Playground

HTML

<input name="txtTest"  type="text" id="txtTest" size="50" onkeyup="CheckKey()"/>

JavaScript

function CheckKey()
{
    var e = window.event;
    var code = e.keyCode ? e.keyCode : e.which;
    if(code === 13)
    {
      alert("You press Enter key.");
    }            
}