what is the purpose of comma (,) after div?
var div, container = document.getElementById("container");
is it for declaring two variables at ones or something else
here is the rest of the code:
for (var i = 0; i < 5; i++) {
div = document.createElement("div");
div.onclick = function() {
alert("This is box #" + i);
};
container.appendChild(div);
}