How do I get the difference between two Dates in JavaScript?

Question

I\'m creating an application which lets you define events with a time frame. I want to automatically fill in the end date when the user selects or changes the start date.

Answer 1

See JsFiddle DEMO

    var date1 = new Date();    
    var date2 = new Date("2025/07/30 21:59:00");
    //Customise date2 for your required future time

    showDiff();

function showDiff(date1, date2){

    var diff = (date2 - date1)/1000;
    diff = Math.abs(Math.floor(diff));

    var days = Math.floor(diff/(24*60*60));
    var leftSec = diff - days * 24*60*60;

    var hrs = Math.floor(leftSec/(60*60));
    var leftSec = leftSec - hrs * 60*60;

    var min = Math.floor(leftSec/(60));
    var leftSec = leftSec - min * 60;

    document.getElementById("showTime").innerHTML = "You have " + days + " days " + hrs + " hours " + min + " minutes and " + leftSec + " seconds before death.";

setTimeout(showDiff,1000);
}

for your HTML Code:

<div id="showTime"></div>

Answer 2

If you use Date objects and then use the getTime() function for both dates it will give you their respective times since Jan 1, 1970 in a number value. You can then get the difference between these numbers.

If that doesn't help you out, check out the complete documentation: http://www.w3schools.com/jsref/jsref_obj_date.asp

Answer 3

JavaScript perfectly supports date difference out of the box

https://jsfiddle.net/b9chris/v5twbe3h/

var msMinute = 60*1000, 
    msDay = 60*60*24*1000,
    a = new Date(2012, 2, 12, 23, 59, 59),
    b = new Date("2013 march 12");


console.log(Math.floor((b - a) / msDay) + ' full days between'); // 364
console.log(Math.floor(((b - a) % msDay) / msMinute) + ' full minutes between'); // 0

---

Now some pitfalls. Try this:

console.log(a - 10); // 1331614798990
console.log(a + 10); // mixed string

So if you have risk of adding a number and Date, convert Date to number directly.

console.log(a.getTime() - 10); // 1331614798990
console.log(a.getTime() + 10); // 1331614799010

My fist example demonstrates the power of Date object but it actually appears to be a time bomb

Answer 4

Depending on your needs, this function will calculate the difference between the 2 days, and return a result in days decimal.

// This one returns a signed decimal. The sign indicates past or future.

this.getDateDiff = function(date1, date2) {
    return (date1.getTime() - date2.getTime()) / (1000 * 60 * 60 * 24);
}

// This one always returns a positive decimal. (Suggested by Koen below)

this.getDateDiff = function(date1, date2) {
    return Math.abs((date1.getTime() - date2.getTime()) / (1000 * 60 * 60 * 24));
}

Answer 5

function compare()
{
  var end_actual_time    = $('#date3').val();

  start_actual_time = new Date();
  end_actual_time = new Date(end_actual_time);

  var diff = end_actual_time-start_actual_time;

  var diffSeconds = diff/1000;
  var HH = Math.floor(diffSeconds/3600);
  var MM = Math.floor(diffSeconds%3600)/60;

  var formatted = ((HH < 10)?("0" + HH):HH) + ":" + ((MM < 10)?("0" + MM):MM)
  getTime(diffSeconds);
}
function getTime(seconds) {
  var days = Math.floor(leftover / 86400);

  //how many seconds are left
  leftover = leftover - (days * 86400);

  //how many full hours fits in the amount of leftover seconds
  var hours = Math.floor(leftover / 3600);

  //how many seconds are left
  leftover = leftover - (hours * 3600);

  //how many minutes fits in the amount of leftover seconds
  var minutes = leftover / 60;

  //how many seconds are left
  //leftover = leftover - (minutes * 60);
  alert(days + ':' + hours + ':' + minutes);
}

Answer 6

alternative modificitaion extended code..

http://jsfiddle.net/vvGPQ/48/

showDiff();

function showDiff(){
var date1 = new Date("2013/01/18 06:59:00");   
var date2 = new Date();
//Customise date2 for your required future time

var diff = (date2 - date1)/1000;
var diff = Math.abs(Math.floor(diff));

var years = Math.floor(diff/(365*24*60*60));
var leftSec = diff - years * 365*24*60*60;

var month = Math.floor(leftSec/((365/12)*24*60*60));
var leftSec = leftSec - month * (365/12)*24*60*60;    

var days = Math.floor(leftSec/(24*60*60));
var leftSec = leftSec - days * 24*60*60;

var hrs = Math.floor(leftSec/(60*60));
var leftSec = leftSec - hrs * 60*60;

var min = Math.floor(leftSec/(60));
var leftSec = leftSec - min * 60;




document.getElementById("showTime").innerHTML = "You have " + years + " years "+ month + " month " + days + " days " + hrs + " hours " + min + " minutes and " + leftSec + " seconds the life time has passed.";

setTimeout(showDiff,1000);
}