window.onload = function() {
var cont = document.querySelector('body');
cont.innerHTML = cont.innerHTML + '<div id="button_up"></div>';
var pic = new Image();
pic.src = "static.png";
pic.id = "arrow";
var button = document.getElementById('button_up');
button.appendChild(pic);
document.getElementById('arrow').onmouseover = function() {
pic.src = "onMouseOver.png";
};
document.getElementById('arrow').onmouseout = function() {
pic.src = "static.png";
};
}