JSFiddle - React, Tailwind, and code Playground

by Qwerty_Wasd

HTML

<input id="date" type="date" value="15.11.2018" required pattern="[0-9]{2}.[0-9]{2}.[0-9]{4}">
<div id="result"></div>

JavaScript

document.getElementById('date').oninput = () => {
	let myDate = new Date(document.getElementById('date').value);
	document.getElementById('result').textContent = ["Воскресенье", "Понедельник", "Вторник", "Среда", "Четверг", "Пятница", "Суббота"][myDate.getDay()];
}