JSFiddle - React, Tailwind, and code Playground

HTML

<form action="#" id="contact">
    <input type="text" class="req"><br>
    <input type="text" class="req"><br>
    <input type="text" class="req"><br>
    <textarea name="" id="" cols="30" rows="10" class="req"></textarea><br>
    <input type="submit">
                    
</form>

JavaScript

document.getElementById('contact').onsubmit = function() {
        var req = this.getElementsByClassName('req').length;
        console.log(req);
        return false;
    };