Loop through a date range with JavaScript

Question

Here's a way to do it by making use of the way adding one day causes the date to roll over to the next month if necessary, and without messing around with milliseconds. Daylight savings aren't an issue either.

var now = new Date();
var daysOfYear = [];
for (var d = new Date(2012, 0, 1); d <= now; d.setDate(d.getDate() + 1)) {
    daysOfYear.push(new Date(d));
}

Note that if you want to store the date, you'll need to make a new one (as above with new Date(d)), or else you'll end up with every stored date being the final value of d in the loop.

Based on Tom Gullen´s answer.

var start = new Date("02/05/2013");
var end = new Date("02/10/2013");


var loop = new Date(start);
while(loop <= end){
   alert(loop);           

   var newDate = loop.setDate(loop.getDate() + 1);
   loop = new Date(newDate);
}

I think I found an even simpler answer, if you allow yourself to use Moment.js:

// cycle through last five days, today included
// you could also cycle through any dates you want, mostly for
// making this snippet not time aware
const currentMoment = moment().subtract(4, 'days');
const endMoment = moment().add(1, 'days');
while (currentMoment.isBefore(endMoment, 'day')) {
  console.log(`Loop at ${currentMoment.format('YYYY-MM-DD')}`);
  currentMoment.add(1, 'days');
}

<script src="https://cdn.jsdelivr.net/npm/moment@2/moment.min.js"></script>

If startDate and endDate are indeed date objects you could convert them to number of milliseconds since midnight Jan 1, 1970, like this:

var startTime = startDate.getTime(), endTime = endDate.getTime();

Then you could loop from one to another incrementing loopTime by 86400000 (1000*60*60*24) - number of milliseconds in one day:

for(loopTime = startTime; loopTime < endTime; loopTime += 86400000)
{
    var loopDay=new Date(loopTime)
    //use loopDay as you wish
}

Here simple working code, worked for me

var from = new Date(2012,0,1);
var to = new Date(2012,1,20);
    
// loop for every day
for (var day = from; day <= to; day.setDate(day.getDate() + 1)) {
      
   // your day is here

}