Maybe this is what you want?
function setImage(i) {
var image = "<img src=images/sl" + i + ".jpg" + " width="500" height="300" style="margin-left:400px;" />";
document.getElementById("slider").innerHTML = image;
}
function loopImages(i) {
setImage(i); // set current Image
if (i == 5) {
i = 1; // reset the counter
}
setTimeout(function () {
loopImages(i++);
}, "600"); // set next image in 600 ms
}
loopImages(1);
Don’t know if you want it to stop on image 5 or to loop forever…