JSFiddle - React, Tailwind, and code Playground

HTML

<input type="text" id="empemail" onblur="emailValidation('empemail')" name="email" placeholder="eg: [email protected]" required="">

JavaScript

function emailValidation(id)
            {
       var emailPattern = /^\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*$/;
       var email = document.getElementById(id).value
                if (emailPattern.test(email) === false)
                {
                    alert("not a valid email address.");
                 }            
            }