JSFiddle - React, Tailwind, and code Playground

HTML

<script>

</script>


<form name="myForm" action="demo_form.asp" onsubmit="return validateForm();" method="post">
Email: <input type="text" name="email">
<input type="submit" value="Submit">
</form>

<h2 id='result'></h2>

JavaScript

function validateForm() {
    var x = document.forms["myForm"]["email"].value;
    var atpos = x.indexOf("@");
    var dotpos = x.lastIndexOf(".");
    if (atpos<1 || dotpos<atpos+2 || dotpos+2>=x.length) {
        $("#result").text("");
        $("#result").text(x + " is valid :)");
        return false;
    }
    else {
        alert("OK");
    }
}