Round a timestamp to the nearest date

Question

I need to group a bunch of items in my web app by date created.

Each item has an exact timestamp, e.g. 1417628530199. I\'m using Moment.js and its \"tim

Answer 1

Using Moment.js, you can use the following code to round everything to the beginning of the day:

moment().startOf('day').toString();
// -> Prints out "Fri Dec 05 2014 00:00:00 GMT-0800"

You can read more about startOf() in the docs.

Answer 2

Here is a clean way to get just the date in one line with no dependencies:

let d = new Date().setHours(0, 0, 0, 0);

Answer 3

Just construct a new Date from the existing one using only the year, month, and date. Add half a day to ensure that it is the closest date.

var offset = new Date(Date.now() +43200000);
var rounded = new Date(offset .getFullYear(),offset .getMonth(),offset .getDate());
console.log(new Date());
console.log(rounded);

Since this seems to have a small footprint, it can also be useful to extend the prototype to include it in the Date "class".

Date.prototype.round = function(){
    var dateObj = new Date(+this+43200000);
    return new Date(dateObj.getFullYear(), dateObj.getMonth(), dateObj.getDate());
};
console.log(new Date().round());

Minimized:

Date.prototype.round = function(){var d = new Date(+this+43200000);return new Date(d.getFullYear(), d.getMonth(), d.getDate());};

Answer 4

Try this:

Date.prototype.formatDate = function() {
   var yyyy = this.getFullYear().toString();
   var mm = (this.getMonth()+1).toString();
   var dd  = this.getDate().toString();
   return yyyy + (mm[1]?mm:"0"+mm[0]) + (dd[1]?dd:"0"+dd[0]);
  };

var utcSeconds = 1417903843000,
    d = new Date(0);

d.setUTCSeconds(Math.round( utcSeconds / 1000.0));

var myTime = (function(){
        var theTime = moment(d.formatDate(), 'YYYYMMDD').startOf('day').fromNow();
        if(theTime.match('hours ago')){
            return 'Today';
        }
        return theTime;
    })();

alert( myTime );

http://jsfiddle.net/cdn5rvck/4/

Answer 5

Well, using js you can do:

var d = new Date(1417628530199);
d.setHours(0);
d.setMinutes(0);
d.setSeconds(0);
d.setMilliseconds(0);

Edit:

After checking several methods, this one seems to be the faster:

function roundDate(timeStamp){
    timeStamp -= timeStamp % (24 * 60 * 60 * 1000);//subtract amount of time since midnight
    timeStamp += new Date().getTimezoneOffset() * 60 * 1000;//add on the timezone offset
    return new Date(timeStamp);
}

You can check difference in speed here: http://jsfiddle.net/juvian/3aqmhn2h/

Answer 6

function roundDownDate(date) {
  if (typeof date !== "object" || !date.getUTCMilliseconds) {
      throw Error("Arg must be a Date object.");
  }
  var offsetMs = date.getTimezoneOffset() * 60 * 1000,
      oneDayMs = 24 * 60 * 60 * 1000;
  return new Date(Math.floor((date.getTime() - offsetMs) / oneDayMs) * oneDayMs + offsetMs);
};

This should work and is pretty fast.