JSFiddle - React, Tailwind, and code Playground

by Hidayat Rifan

HTML

<form>
    <input type="text" id="email" />
    <button type="button" id="submit">Validate</button>
</form>

JavaScript

var submit = document.getElementById('submit');
submit.addEventListener("click", function () {
    var email = document.getElementById('email').value,
        filter = /^([a-zA-Z0-9_.-])+@(([a-zA-Z0-9-])+.)+([a-zA-Z0-9]{2,4})+$/;
    if (!filter.test(email)) {
        alert('Please enter a valid email!');
    }
}, !1)