No, you cannot do that with Javascript. You would need server-side coding if you insist on
alternate redirects. The nearest you could do is redirect to one site if the time in seconds was odd, and to the other if the time in seconds was even. That would be effectively the same thing taken over a period and result in a 50/50 division.
Code:
var now = new Date().getSeconds();
if (now %2 == 0) {
var redirecturl = "link1";
}
else {
var redirecturl = "link2";
}