JSFiddle - React, Tailwind, and code Playground

HTML

<img src="http://jsheroes.io/assets/images/logo/community/JSBelgrade.jpeg" alt="">

JavaScript

let daysArray = ['Воскресенье', 'Понедельник', 'Вторник', 'Среда', 'Четверг', 'Пятница', 'Суббота'];
let day = new Date().getDay();
console.log(daysArray[day]);
let img = document.querySelector('img');
img.onmouseenter = function() {
	this.src='http://jscoderetreat.com/img/why-js.png';
}