Javascript function in setInterval

Question

I have the following code:

var foo=5;
var los= function (){
    alert(foo);};
setInterval(los, 1000);

which works correctly.

If I

Answer 1

Because you're executing los() and then the result of that (single) execution is passed into the setInterval function.

setInterval requires a function passed in, not undefined, which is what los returns. However, it doesn't complain - it just doesn't do anything.