JSFiddle - React, Tailwind, and code Playground

HTML

<input type="email" placeholder="Your email" id="e">
<input type="submit" id="s" onClick="myFunction()">

CSS

input {
  border: 0;
  padding: 10px;
  font-size: 18px;
}

input[type="submit"] {
  background: red;
  color: white;
  border: solid black;
}

JavaScript

function myFunction() {
    const email = document.getElementById("e").value;
    var button = document.getElementById("s").onclick;

		console.log('Test');
    if (email.includes('@'))
    {
      alert("Thank you for subscribing!");
    } else {
      alert("Please enter a valid email.");
    }
  }