JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css">
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/js/bootstrap.min.js"></script>
<button onclick="myFunction()">Try it</button>
<p id="demo" style="text-align: center; color: blue; font-size: 40px;"></p>
<script>
    function myFunction() {
        switch (new Date().getDay()) {
            case 0:
                day = "Sunday";
                document.body.style.backgroundImage = "url('http://lorempixel.com/400/200/sports/1/')";
                break;
            case 1:
                day = "Monday";
                document.body.style.backgroundImage = "url('http://lorempixel.com/400/200/sports/1/')";
                break;
            case 2:
                day = "Tuesday";
                document.body.style.backgroundImage = "url('http://lorempixel.com/400/200/sports/1/')";
                break;
            case 3:
                day = "Wednesday";
                document.body.style.backgroundImage = "url('http://lorempixel.com/400/200/sports/1/')";
                break;
            case 4:
                day = "Thursday";
                document.body.style.backgroundImage = "url('http://lorempixel.com/400/200/sports/1/')";
                break;
            case 5:
                day = "Friday";
                document.body.style.backgroundImage = "url('http://lorempixel.com/400/200/sports/1/')";
                break;
            case 6:
                day = "Saturday";
                document.body.style.backgroundImage = "url('http://lorempixel.com/400/200/sports/1/')";
                break;
        }
        document.getElementById("demo").innerHTML = "Today is " + day;


    }
</script>