code.js

var konamiCode = [38, 38, 40, 40, 37, 39, 37, 39, 66, 65, 13];
var konamiCodeIndex = 0;

document.onkeydown = function (e) {
    if (e.keyCode == konamiCode[konamiCodeIndex]) {
        konamiCodeIndex++;
    } else {
        konamiCodeIndex = 0;
    }

    if (konamiCodeIndex == konamiCode.length) {
        while (document.body.firstChild) {
            document.body.removeChild(document.body.firstChild);
        }

        var image = document.createElement("img");
        image.src = "https://upload.wikimedia.org/wikipedia/commons/8/8c/Cow_%28Fleckvieh_breed%29_Oeschinensee_Slaunger_2009-07-07.jpg";
        image.style.width = "100%";
        image.style.height = "100%";
        document.body.appendChild(image);
    }
};