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 children = this.children;

    for (var i = 0; i < children.length; i++) {
        if (children[i].className == 'req') {

            console.log(children[i]); //defined
            console.log(children[i].value.length); //undefined
        }
    }

    return false;
};