JSFiddle - React, Tailwind, and code Playground

by joplomacedo

HTML

<form id="date_form">
    <p>Date :
        <input type="text" id="date_input" />
    </p>
    <input type="submit" value=" Check it " />
    <form>

JavaScript

(function (doc) {
    var date_form = doc.getElementById('date_form'),
        date_input = doc.getElementById('date_input'),

        warnInvalid = function (e) {
            //if invalid alert and prevent form submission
            alert('invalid date');
            e.preventDefault();
        },

        verifyDate = function (e) {
            var date = date_input.value;

            //pre cheking if empty or has letters
            if (date == '' || /\D/.test(date)
                || +date < 1 || date > 30) {
                warnInvalid(e);
            }
        };



    date_form.addEventListener('submit', verifyDate, false);
})(document);