var colors = ["red", "blue", "yellow", "green", "orange", "black", "cyan", "magenta"];
var colorIndex = 0;
function changeColor() {
var col = document.getElementById("changecolor2");
if( colorIndex >= colors.length ) {
colorIndex = 0;
}
col.style.backgroundColor = colors[colorIndex];
colorIndex++;
}
window.onload = changeColor;
Fiddle : http://jsfiddle.net/aslancods/6S46U/