string to date conversion returns NaN - javascript

I'm using a jquery datetime picker plugin and have three textboxes viz., startdate, enddate, difference. plugin works perfectly, startdate string (dd/MM/yyyy HH:mm) format gets converted correctly but enddate string doesn't get converted to Date object and it returns NaN. can anyone help me?
here's my code:-
<script type="text/javascript">
$(document).ready(function () {
$('#<%= txtEndDate.ClientID %>').bootstrapMaterialDatePicker
({
weekStart: 0, format: 'DD/MM/YYYY HH:mm', shortTime: true
});
$('#<%= txtStartDate.ClientID %>').bootstrapMaterialDatePicker
({
weekStart: 0, format: 'DD/MM/YYYY HH:mm', shortTime: true
}).on('change', function (e, date) {
$('#<%= txtEndDate.ClientID %>').bootstrapMaterialDatePicker('setMinDate', date);
});
$('.mb').change(function () {
var start = $('#<%= txtStartDate.ClientID %>').val();
alert('start:-'+start);
var end1 = $('#<%= txtEndDate.ClientID %>').val();
alert('end:-'+end1);
if (start != "" && end1 != "") {
var eDate = Date.parse(end1);
var sDate = Date.parse(start);
alert(sDate);
alert(eDate);// gives NaN
var diff = Math.abs(eDate - sDate);
alert(diff);
// get total seconds between the times
var delta = diff / 1000;
// calculate (and subtract) whole days
var days = Math.floor(delta / 86400);
delta -= days * 86400;
// calculate (and subtract) whole hours
var hours = Math.floor(delta / 3600) % 24;
delta -= hours * 3600;
// calculate (and subtract) whole minutes
var minutes = Math.floor(delta / 60) % 60;
delta -= minutes * 60;
// what's left is seconds
var seconds = delta % 60;
$('#<%= txtDifference.ClientID %>').val(parseInt(days) + ":" + parseInt(hours) + ":" + parseInt(minutes) + ":" + parseInt(seconds));
}
})
});
</script>
alert('start:-'+start); gives start:-12/11/2017 20:52alert('end:-'+end1); gives end:-13/11/2017 20:54
alert(sDate); gives 1513005720000
but alert(eDate); gives NaN

After some research and getting harassed by plain javascript I switched to moment.js and voila! I got the result of a valid date difference. I just replaced my javascript code with:-
var d1 = moment(startDateString, "DD-MM-YYYY HH:mm");
var d2 = moment(endDateString, "DD-MM-YYYY HH:mm");
This worked smoothly.

Date.parse() has some quirky support across browsers. Like some strings parsed on Chrome returns NaN in FF.
So, I suggest writing a utility function that composes your date from the string format you are using.
Here is an regex based snippet to extract the dd, mm and yyyy from the string and compose it to a Date object.
function getTimeFromString (formattedString) {
var a = formattedString.match(/(\d{2})\/(\d{2})\/(\d{4})\s(\d{2}):(\d{2})/)
var d = new Date()
d.setDate(a[1]), d.setMonth[a[2] - 1], d.setYear(a[3]), d.setHours(a[4]), d.setMinutes(a[5])
return d.getTime()
}
And, use getTimeFromString to do your calculations. Hope this helps.

This unexpected behavior is probably due to date string format that you are trying to parse. If you look closely at MDN dateString explanation you can see
A string representing an RFC2822 or (a variant of) ISO 8601 date (other formats may be used, but results may be unexpected).
Also take a look at return value explained
If the argument doesn't represent a valid date, NaN is returned.
So, I have tried following and got 1513022040000 as result. Hope it helps
var dateString = new Date('12/11/2017 20:54');
var result = Date.parse(dateString);
console.log(result)

Related

Getting error when try to get difference tow date? [duplicate]

This question already has answers here:
How to calculate number of days between two dates?
(42 answers)
Closed 7 years ago.
How do I get the difference between 2 dates in full days (I don't want any fractions of a day)
var date1 = new Date('7/11/2010');
var date2 = new Date('12/12/2010');
var diffDays = date2.getDate() - date1.getDate();
alert(diffDays)
I tried the above but this did not work.
Here is one way:
const date1 = new Date('7/13/2010');
const date2 = new Date('12/15/2010');
const diffTime = Math.abs(date2 - date1);
const diffDays = Math.ceil(diffTime / (1000 * 60 * 60 * 24));
console.log(diffTime + " milliseconds");
console.log(diffDays + " days");
Observe that we need to enclose the date in quotes. The rest of the code gets the time difference in milliseconds and then divides to get the number of days. Date expects mm/dd/yyyy format.
A more correct solution
... since dates naturally have time-zone information, which can span regions with different day light savings adjustments
Previous answers to this question don't account for cases where the two dates in question span a daylight saving time (DST) change. The date on which the DST change happens will have a duration in milliseconds which is != 1000*60*60*24, so the typical calculation will fail.
You can work around this by first normalizing the two dates to UTC, and then calculating the difference between those two UTC dates.
Now, the solution can be written as,
// a and b are javascript Date objects
function dateDiffInDays(a, b) {
const _MS_PER_DAY = 1000 * 60 * 60 * 24;
// Discard the time and time-zone information.
const utc1 = Date.UTC(a.getFullYear(), a.getMonth(), a.getDate());
const utc2 = Date.UTC(b.getFullYear(), b.getMonth(), b.getDate());
return Math.floor((utc2 - utc1) / _MS_PER_DAY);
}
// test it
const a = new Date("2017-01-01"),
b = new Date("2017-07-25"),
difference = dateDiffInDays(a, b);
console.log(difference + ' days')
This works because UTC time never observes DST. See Does UTC observe daylight saving time?
p.s. After discussing some of the comments on this answer, once you've understood the issues with javascript dates that span a DST boundary, there is likely more than just one way to solve it. What I provided above is a simple (and tested) solution. I'd be interested to know if there is a simple arithmetic/math based solution instead of having to instantiate the two new Date objects. That could potentially be faster.
var date1 = new Date("7/11/2010");
var date2 = new Date("8/11/2010");
var diffDays = parseInt((date2 - date1) / (1000 * 60 * 60 * 24), 10);
alert(diffDays )
I tried lots of ways, and found that using datepicker was the best, but the date format causes problems with JavaScript....
So here's my answer and can be run out of the box.
<input type="text" id="startdate">
<input type="text" id="enddate">
<input type="text" id="days">
<script src="https://code.jquery.com/jquery-1.8.3.js"></script>
<script src="https://code.jquery.com/ui/1.10.0/jquery-ui.js"></script>
<link rel="stylesheet" href="http://code.jquery.com/ui/1.10.3/themes/redmond/jquery-ui.css" />
<script>
$(document).ready(function() {
$( "#startdate,#enddate" ).datepicker({
changeMonth: true,
changeYear: true,
firstDay: 1,
dateFormat: 'dd/mm/yy',
})
$( "#startdate" ).datepicker({ dateFormat: 'dd-mm-yy' });
$( "#enddate" ).datepicker({ dateFormat: 'dd-mm-yy' });
$('#enddate').change(function() {
var start = $('#startdate').datepicker('getDate');
var end = $('#enddate').datepicker('getDate');
if (start<end) {
var days = (end - start)/1000/60/60/24;
$('#days').val(days);
}
else {
alert ("You cant come back before you have been!");
$('#startdate').val("");
$('#enddate').val("");
$('#days').val("");
}
}); //end change function
}); //end ready
</script>
a Fiddle can be seen here DEMO
This is the code to subtract one date from another. This example converts the dates to objects as the getTime() function won't work unless it's an Date object.
var dat1 = document.getElementById('inputDate').value;
var date1 = new Date(dat1)//converts string to date object
alert(date1);
var dat2 = document.getElementById('inputFinishDate').value;
var date2 = new Date(dat2)
alert(date2);
var oneDay = 24 * 60 * 60 * 1000; // hours*minutes*seconds*milliseconds
var diffDays = Math.abs((date1.getTime() - date2.getTime()) / (oneDay));
alert(diffDays);

count number of days between today's date and from <p> tag in javascript [duplicate]

This question already has answers here:
How to calculate number of days between two dates?
(42 answers)
Closed 7 years ago.
How do I get the difference between 2 dates in full days (I don't want any fractions of a day)
var date1 = new Date('7/11/2010');
var date2 = new Date('12/12/2010');
var diffDays = date2.getDate() - date1.getDate();
alert(diffDays)
I tried the above but this did not work.
Here is one way:
const date1 = new Date('7/13/2010');
const date2 = new Date('12/15/2010');
const diffTime = Math.abs(date2 - date1);
const diffDays = Math.ceil(diffTime / (1000 * 60 * 60 * 24));
console.log(diffTime + " milliseconds");
console.log(diffDays + " days");
Observe that we need to enclose the date in quotes. The rest of the code gets the time difference in milliseconds and then divides to get the number of days. Date expects mm/dd/yyyy format.
A more correct solution
... since dates naturally have time-zone information, which can span regions with different day light savings adjustments
Previous answers to this question don't account for cases where the two dates in question span a daylight saving time (DST) change. The date on which the DST change happens will have a duration in milliseconds which is != 1000*60*60*24, so the typical calculation will fail.
You can work around this by first normalizing the two dates to UTC, and then calculating the difference between those two UTC dates.
Now, the solution can be written as,
// a and b are javascript Date objects
function dateDiffInDays(a, b) {
const _MS_PER_DAY = 1000 * 60 * 60 * 24;
// Discard the time and time-zone information.
const utc1 = Date.UTC(a.getFullYear(), a.getMonth(), a.getDate());
const utc2 = Date.UTC(b.getFullYear(), b.getMonth(), b.getDate());
return Math.floor((utc2 - utc1) / _MS_PER_DAY);
}
// test it
const a = new Date("2017-01-01"),
b = new Date("2017-07-25"),
difference = dateDiffInDays(a, b);
console.log(difference + ' days')
This works because UTC time never observes DST. See Does UTC observe daylight saving time?
p.s. After discussing some of the comments on this answer, once you've understood the issues with javascript dates that span a DST boundary, there is likely more than just one way to solve it. What I provided above is a simple (and tested) solution. I'd be interested to know if there is a simple arithmetic/math based solution instead of having to instantiate the two new Date objects. That could potentially be faster.
var date1 = new Date("7/11/2010");
var date2 = new Date("8/11/2010");
var diffDays = parseInt((date2 - date1) / (1000 * 60 * 60 * 24), 10);
alert(diffDays )
I tried lots of ways, and found that using datepicker was the best, but the date format causes problems with JavaScript....
So here's my answer and can be run out of the box.
<input type="text" id="startdate">
<input type="text" id="enddate">
<input type="text" id="days">
<script src="https://code.jquery.com/jquery-1.8.3.js"></script>
<script src="https://code.jquery.com/ui/1.10.0/jquery-ui.js"></script>
<link rel="stylesheet" href="http://code.jquery.com/ui/1.10.3/themes/redmond/jquery-ui.css" />
<script>
$(document).ready(function() {
$( "#startdate,#enddate" ).datepicker({
changeMonth: true,
changeYear: true,
firstDay: 1,
dateFormat: 'dd/mm/yy',
})
$( "#startdate" ).datepicker({ dateFormat: 'dd-mm-yy' });
$( "#enddate" ).datepicker({ dateFormat: 'dd-mm-yy' });
$('#enddate').change(function() {
var start = $('#startdate').datepicker('getDate');
var end = $('#enddate').datepicker('getDate');
if (start<end) {
var days = (end - start)/1000/60/60/24;
$('#days').val(days);
}
else {
alert ("You cant come back before you have been!");
$('#startdate').val("");
$('#enddate').val("");
$('#days').val("");
}
}); //end change function
}); //end ready
</script>
a Fiddle can be seen here DEMO
This is the code to subtract one date from another. This example converts the dates to objects as the getTime() function won't work unless it's an Date object.
var dat1 = document.getElementById('inputDate').value;
var date1 = new Date(dat1)//converts string to date object
alert(date1);
var dat2 = document.getElementById('inputFinishDate').value;
var date2 = new Date(dat2)
alert(date2);
var oneDay = 24 * 60 * 60 * 1000; // hours*minutes*seconds*milliseconds
var diffDays = Math.abs((date1.getTime() - date2.getTime()) / (oneDay));
alert(diffDays);

How to calculate number of days between two dates

I have two input dates taking from Date Picker control. I have selected start date 2/2/2012 and end date 2/7/2012. I have written following code for that.
I should get result as 6 but I am getting 5.
function SetDays(invoker) {
var start = $find('<%=StartWebDatePicker.ClientID%>').get_value();
var end = $find('<%=EndWebDatePicker.ClientID%>').get_value();
var oneDay=1000 * 60 * 60 * 24;
var difference_ms = Math.abs(end.getTime() - start.getTime())
var diffValue = Math.round(difference_ms / oneDay);
}
Can anyone tell me how I can get exact difference?
http://momentjs.com/ or https://date-fns.org/
From Moment docs:
var a = moment([2007, 0, 29]);
var b = moment([2007, 0, 28]);
a.diff(b, 'days') // =1
or to include the start:
a.diff(b, 'days')+1 // =2
Beats messing with timestamps and time zones manually.
Depending on your specific use case, you can either
Use a/b.startOf('day') and/or a/b.endOf('day') to force the diff to be inclusive or exclusive at the "ends" (as suggested by #kotpal in the comments).
Set third argument true to get a floating point diff which you can then Math.floor, Math.ceil or Math.round as needed.
Option 2 can also be accomplished by getting 'seconds' instead of 'days' and then dividing by 24*60*60.
If you are using moment.js you can do it easily.
var start = moment("2018-03-10", "YYYY-MM-DD");
var end = moment("2018-03-15", "YYYY-MM-DD");
//Difference in number of days
moment.duration(start.diff(end)).asDays();
//Difference in number of weeks
moment.duration(start.diff(end)).asWeeks();
If you want to find difference between a given date and current date in number of days (ignoring time), make sure to remove time from moment object of current date as below
moment().startOf('day')
To find difference between a given date and current date in number of days
var given = moment("2018-03-10", "YYYY-MM-DD");
var current = moment().startOf('day');
//Difference in number of days
moment.duration(given.diff(current)).asDays();
Try this Using moment.js (Its quite easy to compute date operations in javascript)
firstDate.diff(secondDate, 'days', false);// true|false for fraction value
Result will give you number of days in integer.
Try:
//Difference in days
var diff = Math.floor(( start - end ) / 86400000);
alert(diff);
This works for me:
const from = '2019-01-01';
const to = '2019-01-08';
Math.abs(
moment(from, 'YYYY-MM-DD')
.startOf('day')
.diff(moment(to, 'YYYY-MM-DD').startOf('day'), 'days')
) + 1
);
I made a quick re-usable function in ES6 using Moment.js.
const getDaysDiff = (start_date, end_date, date_format = 'YYYY-MM-DD') => {
const getDateAsArray = (date) => {
return moment(date.split(/\D+/), date_format);
}
return getDateAsArray(end_date).diff(getDateAsArray(start_date), 'days') + 1;
}
console.log(getDaysDiff('2019-10-01', '2019-10-30'));
console.log(getDaysDiff('2019/10/01', '2019/10/30'));
console.log(getDaysDiff('2019.10-01', '2019.10 30'));
console.log(getDaysDiff('2019 10 01', '2019 10 30'));
console.log(getDaysDiff('+++++2019!!/###10/$$01', '2019-10-30'));
console.log(getDaysDiff('2019-10-01-2019', '2019-10-30'));
console.log(getDaysDiff('10-01-2019', '10-30-2019', 'MM-DD-YYYY'));
console.log(getDaysDiff('10-01-2019', '10-30-2019'));
console.log(getDaysDiff('10-01-2019', '2019-10-30', 'MM-DD-YYYY'));
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.24.0/moment.js"></script>
Also you can use this code: moment("yourDateHere", "YYYY-MM-DD").fromNow(). This will calculate the difference between today and your provided date.
// today
const date = new Date();
// tomorrow
const nextDay = new Date(new Date().getTime() + 24 * 60 * 60 * 1000);
// Difference in time
const Difference_In_Time = nextDay.getTime() - date.getTime();
// Difference in Days
const Difference_In_Days = Difference_In_Time / (1000 * 3600 * 24);

Get difference between 2 dates in JavaScript? [duplicate]

This question already has answers here:
How to calculate number of days between two dates?
(42 answers)
Closed 7 years ago.
How do I get the difference between 2 dates in full days (I don't want any fractions of a day)
var date1 = new Date('7/11/2010');
var date2 = new Date('12/12/2010');
var diffDays = date2.getDate() - date1.getDate();
alert(diffDays)
I tried the above but this did not work.
Here is one way:
const date1 = new Date('7/13/2010');
const date2 = new Date('12/15/2010');
const diffTime = Math.abs(date2 - date1);
const diffDays = Math.ceil(diffTime / (1000 * 60 * 60 * 24));
console.log(diffTime + " milliseconds");
console.log(diffDays + " days");
Observe that we need to enclose the date in quotes. The rest of the code gets the time difference in milliseconds and then divides to get the number of days. Date expects mm/dd/yyyy format.
A more correct solution
... since dates naturally have time-zone information, which can span regions with different day light savings adjustments
Previous answers to this question don't account for cases where the two dates in question span a daylight saving time (DST) change. The date on which the DST change happens will have a duration in milliseconds which is != 1000*60*60*24, so the typical calculation will fail.
You can work around this by first normalizing the two dates to UTC, and then calculating the difference between those two UTC dates.
Now, the solution can be written as,
// a and b are javascript Date objects
function dateDiffInDays(a, b) {
const _MS_PER_DAY = 1000 * 60 * 60 * 24;
// Discard the time and time-zone information.
const utc1 = Date.UTC(a.getFullYear(), a.getMonth(), a.getDate());
const utc2 = Date.UTC(b.getFullYear(), b.getMonth(), b.getDate());
return Math.floor((utc2 - utc1) / _MS_PER_DAY);
}
// test it
const a = new Date("2017-01-01"),
b = new Date("2017-07-25"),
difference = dateDiffInDays(a, b);
console.log(difference + ' days')
This works because UTC time never observes DST. See Does UTC observe daylight saving time?
p.s. After discussing some of the comments on this answer, once you've understood the issues with javascript dates that span a DST boundary, there is likely more than just one way to solve it. What I provided above is a simple (and tested) solution. I'd be interested to know if there is a simple arithmetic/math based solution instead of having to instantiate the two new Date objects. That could potentially be faster.
var date1 = new Date("7/11/2010");
var date2 = new Date("8/11/2010");
var diffDays = parseInt((date2 - date1) / (1000 * 60 * 60 * 24), 10);
alert(diffDays )
I tried lots of ways, and found that using datepicker was the best, but the date format causes problems with JavaScript....
So here's my answer and can be run out of the box.
<input type="text" id="startdate">
<input type="text" id="enddate">
<input type="text" id="days">
<script src="https://code.jquery.com/jquery-1.8.3.js"></script>
<script src="https://code.jquery.com/ui/1.10.0/jquery-ui.js"></script>
<link rel="stylesheet" href="http://code.jquery.com/ui/1.10.3/themes/redmond/jquery-ui.css" />
<script>
$(document).ready(function() {
$( "#startdate,#enddate" ).datepicker({
changeMonth: true,
changeYear: true,
firstDay: 1,
dateFormat: 'dd/mm/yy',
})
$( "#startdate" ).datepicker({ dateFormat: 'dd-mm-yy' });
$( "#enddate" ).datepicker({ dateFormat: 'dd-mm-yy' });
$('#enddate').change(function() {
var start = $('#startdate').datepicker('getDate');
var end = $('#enddate').datepicker('getDate');
if (start<end) {
var days = (end - start)/1000/60/60/24;
$('#days').val(days);
}
else {
alert ("You cant come back before you have been!");
$('#startdate').val("");
$('#enddate').val("");
$('#days').val("");
}
}); //end change function
}); //end ready
</script>
a Fiddle can be seen here DEMO
This is the code to subtract one date from another. This example converts the dates to objects as the getTime() function won't work unless it's an Date object.
var dat1 = document.getElementById('inputDate').value;
var date1 = new Date(dat1)//converts string to date object
alert(date1);
var dat2 = document.getElementById('inputFinishDate').value;
var date2 = new Date(dat2)
alert(date2);
var oneDay = 24 * 60 * 60 * 1000; // hours*minutes*seconds*milliseconds
var diffDays = Math.abs((date1.getTime() - date2.getTime()) / (oneDay));
alert(diffDays);

How to subtract days from a plain Date?

Want to improve this post? Provide detailed answers to this question, including citations and an explanation of why your answer is correct. Answers without enough detail may be edited or deleted.
Is there an easy way of taking a olain JavaScript Date (e.g. today) and going back X days?
So, for example, if I want to calculate the date 5 days before today.
Try something like this:
var d = new Date();
d.setDate(d.getDate()-5);
Note that this modifies the date object and returns the time value of the updated date.
var d = new Date();
document.write('Today is: ' + d.toLocaleString());
d.setDate(d.getDate() - 5);
document.write('<br>5 days ago was: ' + d.toLocaleString());
var dateOffset = (24*60*60*1000) * 5; //5 days
var myDate = new Date();
myDate.setTime(myDate.getTime() - dateOffset);
If you're performing lots of headachy date manipulation throughout your web application, DateJS will make your life much easier:
http://simonwillison.net/2007/Dec/3/datejs/
It goes something like this:
var d = new Date(); // today!
var x = 5; // go back 5 days!
d.setDate(d.getDate() - x);
I noticed that the getDays+ X doesn't work over day/month boundaries. Using getTime works as long as your date is not before 1970.
var todayDate = new Date(), weekDate = new Date();
weekDate.setTime(todayDate.getTime()-(7*24*3600000));
If you want it all on one line instead.
5 days from today
//past
var fiveDaysAgo = new Date(new Date().setDate(new Date().getDate() - 5));
//future
var fiveDaysInTheFuture = new Date(new Date().setDate(new Date().getDate() + 5));
5 days from a specific date
var pastDate = new Date('2019-12-12T00:00:00');
//past
var fiveDaysAgo = new Date(new Date().setDate(pastDate.getDate() - 5));
//future
var fiveDaysInTheFuture = new Date(new Date().setDate(pastDate.getDate() + 5));
I wrote a function you can use.
function AddOrSubractDays(startingDate, number, add) {
if (add) {
return new Date(new Date().setDate(startingDate.getDate() + number));
} else {
return new Date(new Date().setDate(startingDate.getDate() - number));
}
}
console.log('Today : ' + new Date());
console.log('Future : ' + AddOrSubractDays(new Date(), 5, true));
console.log('Past : ' + AddOrSubractDays(new Date(), 5, false));
I find a problem with the getDate()/setDate() method is that it too easily turns everything into milliseconds, and the syntax is sometimes hard for me to follow.
Instead I like to work off the fact that 1 day = 86,400,000 milliseconds.
So, for your particular question:
today = new Date()
days = 86400000 //number of milliseconds in a day
fiveDaysAgo = new Date(today - (5*days))
Works like a charm.
I use this method all the time for doing rolling 30/60/365 day calculations.
You can easily extrapolate this to create units of time for months, years, etc.
get moment.js. All the cool kids use it. It has more formatting options, etc. Where
var n = 5;
var dateMnsFive = moment(<your date>).subtract(n , 'day');
Optional! Convert to JS Date obj for Angular binding.
var date = new Date(dateMnsFive.toISOString());
Optional! Format
var date = dateMnsFive.format("YYYY-MM-DD");
A few of the existing solutions were close, but not quite exactly what I wanted. This function works with both positive or negative values and handles boundary cases.
function addDays(date, days) {
return new Date(
date.getFullYear(),
date.getMonth(),
date.getDate() + days,
date.getHours(),
date.getMinutes(),
date.getSeconds(),
date.getMilliseconds()
);
}
Without using the second variable, you can replace 7 for with your back x days:
let d=new Date(new Date().getTime() - (7 * 24 * 60 * 60 * 1000))
I made this prototype for Date so that I could pass negative values to subtract days and positive values to add days.
if(!Date.prototype.adjustDate){
Date.prototype.adjustDate = function(days){
var date;
days = days || 0;
if(days === 0){
date = new Date( this.getTime() );
} else if(days > 0) {
date = new Date( this.getTime() );
date.setDate(date.getDate() + days);
} else {
date = new Date(
this.getFullYear(),
this.getMonth(),
this.getDate() - Math.abs(days),
this.getHours(),
this.getMinutes(),
this.getSeconds(),
this.getMilliseconds()
);
}
this.setTime(date.getTime());
return this;
};
}
So, to use it i can simply write:
var date_subtract = new Date().adjustDate(-4),
date_add = new Date().adjustDate(4);
I like doing the maths in milliseconds. So use Date.now()
var newDate = Date.now() + -5*24*3600*1000; // date 5 days ago in milliseconds
and if you like it formatted
new Date(newDate).toString(); // or .toUTCString or .toISOString ...
NOTE: Date.now() doesn't work in older browsers (eg IE8 I think). Polyfill here.
UPDATE June 2015
#socketpair pointed out my sloppiness. As s/he says "Some day in year have 23 hours, and some 25 due to timezone rules".
To expand on that, the answer above will have daylightsaving inaccuracies in the case where you want to calculate the LOCAL day 5 days ago in a timezone with daylightsaving changes and you
assume (wrongly) that Date.now() gives you the current LOCAL now time, or
use .toString() which returns the local date and therefore is incompatible with the Date.now() base date in UTC.
However, it works if you're doing your math all in UTC, eg
A. You want the UTC date 5 days ago from NOW (UTC)
var newDate = Date.now() + -5*24*3600*1000; // date 5 days ago in milliseconds UTC
new Date(newDate).toUTCString(); // or .toISOString(), BUT NOT toString
B. You start with a UTC base date other than "now", using Date.UTC()
newDate = new Date(Date.UTC(2015, 3, 1)).getTime() + -5*24*3600000;
new Date(newDate).toUTCString(); // or .toISOString BUT NOT toString
split your date into parts, then return a new Date with the adjusted values
function DateAdd(date, type, amount){
var y = date.getFullYear(),
m = date.getMonth(),
d = date.getDate();
if(type === 'y'){
y += amount;
};
if(type === 'm'){
m += amount;
};
if(type === 'd'){
d += amount;
};
return new Date(y, m, d);
}
Remember that the months are zero based, but the days are not. ie new Date(2009, 1, 1) == 01 February 2009, new Date(2009, 1, 0) == 31 January 2009;
Some people suggested using moment.js to make your life easier when handling dates in js. Time has passed since those answers and it is noteworthy, that the authors of moment.js now discourage its use. Mainly due to its size and lack of tree-shaking-support.
If you want to go the library route, use an alternative like Luxon. It is significantly smaller (because of its clever use of the Intl object and support for tree-shaking) and just as versatile as moment.js.
To go back 5 days from today in Luxon, you would do:
import { DateTime } from 'luxon'
DateTime.now().minus({ days: 5 });
function addDays (date, daysToAdd) {
var _24HoursInMilliseconds = 86400000;
return new Date(date.getTime() + daysToAdd * _24HoursInMilliseconds);
};
var now = new Date();
var yesterday = addDays(now, - 1);
var tomorrow = addDays(now, 1);
See the following code, subtract the days from the current date. Also, set the month according to substracted date.
var today = new Date();
var substract_no_of_days = 25;
today.setTime(today.getTime() - substract_no_of_days* 24 * 60 * 60 * 1000);
var substracted_date = (today.getMonth()+1) + "/" +today.getDate() + "/" + today.getFullYear();
alert(substracted_date);
I have created a function for date manipulation. you can add or subtract any number of days, hours, minutes.
function dateManipulation(date, days, hrs, mins, operator) {
date = new Date(date);
if (operator == "-") {
var durationInMs = (((24 * days) * 60) + (hrs * 60) + mins) * 60000;
var newDate = new Date(date.getTime() - durationInMs);
} else {
var durationInMs = (((24 * days) * 60) + (hrs * 60) + mins) * 60000;
var newDate = new Date(date.getTime() + durationInMs);
}
return newDate;
}
Now, call this function by passing parameters. For example, here is a function call for getting date before 3 days from today.
var today = new Date();
var newDate = dateManipulation(today, 3, 0, 0, "-");
Use MomentJS.
function getXDaysBeforeDate(referenceDate, x) {
return moment(referenceDate).subtract(x , 'day').format('MMMM Do YYYY, h:mm:ss a');
}
var yourDate = new Date(); // let's say today
var valueOfX = 7; // let's say 7 days before
console.log(getXDaysBeforeDate(yourDate, valueOfX));
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.22.2/moment.min.js"></script>
The top answers led to a bug in my code where on the first of the month it would set a future date in the current month. Here is what I did,
curDate = new Date(); // Took current date as an example
prvDate = new Date(0); // Date set to epoch 0
prvDate.setUTCMilliseconds((curDate - (5 * 24 * 60 * 60 * 1000))); //Set epoch time
I like the following because it is one line. Not perfect with DST changes but usually good enough for my needs.
var fiveDaysAgo = new Date(new Date() - (1000*60*60*24*5));
Using Modern JavaScript function syntax
const getDaysPastDate = (daysBefore, date = new Date) => new Date(date - (1000 * 60 * 60 * 24 * daysBefore));
console.log(getDaysPastDate(1)); // yesterday
A easy way to manage dates is use Moment.js
You can use add. Example
var startdate = "20.03.2014";
var new_date = moment(startdate, "DD.MM.YYYY");
new_date.add(5, 'days'); //Add 5 days to start date
alert(new_date);
Docs http://momentjs.com/docs/#/manipulating/add/
for me all the combinations worked fine with below code snipplet ,
the snippet is for Angular-2 implementation ,
if you need to add days , pass positive numberofDays , if you need to substract pass negative numberofDays
function addSubstractDays(date: Date, numberofDays: number): Date {
let d = new Date(date);
return new Date(
d.getFullYear(),
d.getMonth(),
(d.getDate() + numberofDays)
);
}
I get good mileage out of date.js:
http://www.datejs.com/
d = new Date();
d.add(-10).days(); // subtract 10 days
Nice!
Website includes this beauty:
Datejs doesn’t just parse strings, it slices them cleanly in two
If you want to both subtract a number of days and format your date in a human readable format, you should consider creating a custom DateHelper object that looks something like this :
var DateHelper = {
addDays : function(aDate, numberOfDays) {
aDate.setDate(aDate.getDate() + numberOfDays); // Add numberOfDays
return aDate; // Return the date
},
format : function format(date) {
return [
("0" + date.getDate()).slice(-2), // Get day and pad it with zeroes
("0" + (date.getMonth()+1)).slice(-2), // Get month and pad it with zeroes
date.getFullYear() // Get full year
].join('/'); // Glue the pieces together
}
}
// With this helper, you can now just use one line of readable code to :
// ---------------------------------------------------------------------
// 1. Get the current date
// 2. Subtract 5 days
// 3. Format it
// 4. Output it
// ---------------------------------------------------------------------
document.body.innerHTML = DateHelper.format(DateHelper.addDays(new Date(), -5));
(see also this Fiddle)
To calculate relative time stamps with a more precise difference than whole days, you can use Date.getTime() and Date.setTime() to work with integers representing the number of milliseconds since a certain epoch—namely, January 1, 1970. For example, if you want to know when it’s 17 hours after right now:
const msSinceEpoch = (new Date()).getTime();
const fortyEightHoursLater = new Date(msSinceEpoch + 48 * 60 * 60 * 1000).toLocaleString();
const fortyEightHoursEarlier = new Date(msSinceEpoch - 48 * 60 * 60 * 1000).toLocaleString();
const fiveDaysAgo = new Date(msSinceEpoch - 120 * 60 * 60 * 1000).toLocaleString();
console.log({msSinceEpoch, fortyEightHoursLater, fortyEightHoursEarlier, fiveDaysAgo})
reference
function daysSinceGivenDate (date) {
const dateInSeconds = Math.floor((new Date().valueOf() - date.valueOf()) / 1000);
const oneDayInSeconds = 86400;
return Math.floor(dateInSeconds / oneDayInSeconds); // casted to int
};
console.log(daysSinceGivenDate(new Date())); // 0
console.log(daysSinceGivenDate(new Date("January 1, 2022 03:24:00"))); // relative...
First arg is the date to start with and second is how mush day you want to increase or reduce to the date
example (1)- pass -1 to reduce date by one day
example (2)- pass 1 to increase date by one day
const EditDay = (date: Date, num: number): Date => {
return new Date(date.getTime() + num * 24 * 60 * 60 * 1000)
}
When setting the date, the date converts to milliseconds, so you need to convert it back to a date:
This method also take into consideration, new year change etc.
function addDays( date, days ) {
var dateInMs = date.setDate(date.getDate() - days);
return new Date(dateInMs);
}
var date_from = new Date();
var date_to = addDays( new Date(), parseInt(days) );
You can using Javascript.
var CurrDate = new Date(); // Current Date
var numberOfDays = 5;
var days = CurrDate.setDate(CurrDate.getDate() + numberOfDays);
alert(days); // It will print 5 days before today
For PHP,
$date = date('Y-m-d', strtotime("-5 days")); // it shows 5 days before today.
echo $date;
Hope it will help you.
I converted into millisecond and deducted days else month and year won't change and logical
var numberOfDays = 10;//number of days need to deducted or added
var date = "01-01-2018"// date need to change
var dt = new Date(parseInt(date.substring(6), 10), // Year
parseInt(date.substring(3,5), 10) - 1, // Month (0-11)
parseInt(date.substring(0,2), 10));
var new_dt = dt.setMilliseconds(dt.getMilliseconds() - numberOfDays*24*60*60*1000);
new_dt = new Date(new_dt);
var changed_date = new_dt.getDate()+"-"+(new_dt.getMonth()+1)+"-"+new_dt.getFullYear();
Hope helps

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