Increment by day in JavaScript

I had a need to iterate over days of a year today in JavaScript.

I figured you could just add “one day” to the date, and that turns out to be true.

This is the test program I wrote to make sure the incrementing worked properly.

var year = 2008;

var endymd = new Date(year+1, 0, 1, 0, 0, 0).getTime();

var days = 0;
for (var ymd=new Date(year, 0, 1, 0, 0, 0);ymd.getTime()<endymd; md.setDate(ymd.getDate()+1)){

The answer is 366, which means that leap year was handled correctly.