JSFiddle - React, Tailwind, and code Playground

by Nick Craver

HTML

<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8/themes/dot-luv/jquery-ui.css">
<form action="#" method="POST" onsubmit="return valid8(this)">
    
    Email: <input type="text" name="email" size="30" />
    <input type="submit" value="clicky-click" />
    
</form>

JavaScript

var pattern = new RegExp("^[0-9a-zA-Z]+@[0-9a-zA-z]+[\.]{1}[0-9a-zA-Z]+[\.]?[0-9a-zA-Z]+$");

function valid8email(field, txt) {
    if (!pattern.test(field.value))
    {
        alert(txt);
        return false;
    }
    else {
        return true;
    }
}

function valid8(form) {
    if (valid8email(form.email, "you must enter an email address") == false) {
        form.email.focus();
        return false;
    }
}