random-bg-color.js

(function(){ 
    function getRandomColor() {
        var letters = '0123456789ABCDEF'.split('');
        var color = '#';
        
        for (var i = 0; i < 6; i++ ) {
            color += letters[Math.floor(Math.random() * 16)];
        }
        
        return color;
    }

    var body = document.querySelector('body');
    
    body.style.backgroundColor = 'white';
    body.innerHTML = '';
    
    document.addEventListener('keydown', function changeBackgroundColor() {
        body.style.backgroundColor = getRandomColor();
    }, false);
}());

For the kid