I am aware that this question was asked multiple times before but the suggested solutions were always something like
var diff = date1 - date2;
My problem is that I want to get the difference in years, months, day, ... ,seconds.
So for example 5y 3m 39d 12h 39i 32s
But simply dividing the difference is too inaccurate for my purpose.
So I can't assume that every month has 30.4375*24*60*60*1000 milliseconds.
I need the exact difference!
So if date1 is the 1st of february and date2 is the 1st of march, it should display 1m not 28d (or 29d in leap years)!
Thank you.
First you need to find out which date is bigger, subtract the dates, and if they turn out to be negative borrow from the larger digit (similar to elementary multi-digit subtraction).
function DateDiff(a,b){
if(b>a){ // We want a-b to be positive
var c=b;
b=a;
a=c;
}
var s=a.getSeconds()-b.getSeconds();
var mi=a.getMinutes()-b.getMinutes();
var h=a.getHours()-b.getHours();
var d=a.getDate()-b.getDate(); // Subtract days
var m=a.getMonth()-b.getMonth(); // Subtract months
var y=a.getYear()-b.getYear(); // Subtract years
if(s<0){
mi--;
s+=60;
}
if(mi<0){
h--;
mi+=60;
}
if(h<0){
d--;
h+=24;
}
if(d<0){ // Need to borrow from months
m--;
d+=new Date(1900+b.getYear(),1+b.getMonth(),0).getDate();
}if(m<0){ // Need to borrow from years
y--;
m+=12;
}
return [y,m,d,h,mi,s];
}
console.log('Mar 1 - Feb 2 (Leap Year):', DateDiff(new Date(2016,1,2),new Date(2016,2,1)));
console.log('Mar 1 - Feb 2 (Reg Year): ',DateDiff(new Date(2015,1,2),new Date(2015,2,1)));
console.log('Feb 1, 2017 - Feb 2, 2016: ',DateDiff(new Date(2017,1,1),new Date(2016,1,2)));
console.log('5:00 - 4:59: ', DateDiff(new Date(2015,7,1,17), new Date(2015,7,1,16,59)));
You can use moment.js to achieve this: ( MomentJS Doc )
var start = moment(date1);
var end = moment(date2);
var diff = end.diff(start)
If you want specific things like difference in days, you can do:
var diff = end.diff(start, 'days')
For what you are describing, you will want to hold the year/month/day in three different variables and directly compare the years using
var yeardiff = date1.GetFullYear() - date2.GetFullYear();
var monthdiff = date1.GetMonth() - date2.GetMonth();
var daydiff = date1.GetDate() - date2.GetDate();
However, you are going to have to do a lot of checking in this. For example, 8/2/2012 - 7/20/2012 is going to give you a 1 month and -18 days, then you have to convert that into days based on the number of days in July. Because of these issues, the other conversion in the OP is actually easier.
Not using any library you could do
function mydiff(aa,bb){var a,b;
if(aa<bb) a=aa,b=bb;
else a=bb,b=aa;
var am=a.getMonth(),ay=a.getFullYear();
var dd=b.getDate()-a.getDate();
var dm=b.getMonth()-am-(dd<0?1:0);
return b.getFullYear()-ay-(dm<0?1:0)+'y, '
+ ((12+dm)%12)+'m, '
+((dd<0?new Date(ay, am+1, 0).getDate():0)+dd)+'d';
}
dd contains the difference 'b minus a in days of month' which can be negative. In that case the month-difference dm has to be reduced by 1 and the (negative) day-difference must be increased by the number of days of the preceding month of date b. I got the formula for "number of days in a particular month" from here. Similar action has to take place with the month- and year-differences dm and dm.
A few samples:
mydiff(new Date(2014,1,2),new Date(2014,2,1)) // "0y, 0m, 27d"
mydiff(new Date(2012,1,1),new Date(2012,2,1)) // "0y, 1m, 0d" (leap year)
mydiff(new Date(2012,1,2),new Date(2012,2,1)) // "0y, 0m, 28d" (leap year)
mydiff(new Date(2014,11,31),new Date(2015,0,1)) // "0y, 0m, 1d" (different years)
mydiff(new Date(2012,10,30),new Date(2013,1,28)) // "0y, 2m, 28d" (different years)
The last example shows that this kind of "calculation" has its limits: compared to "normal" months 28 days are not a full month. On the other hand, compared to the current month February 28 days is a full month. So it could also be argued that a correct response should be "0y, 3m, 0d".
Related
https://jsfiddle.net/yg4bk1wh/
I am trying to create a tool that reports the days remaining -
moment(1583884740000).diff(moment(), 'days')
but this is reporting incorrectly - almost as if the month index is not taken into consideration.
-- also if the days became negative - would want to obtain the value without the polarisation - so intead of "10 days remaining" -- it reads "finished 30 days ago"
-- https://www.calendar-12.com/days_between_dates
scenario 1
Start Date - February 12th
End Date - March 10th
total days between the two dates - 27 days
remaining days from now until end day - 33 days
^ campaign has yet to start
scenario 2
Start Date -January 6
End Date - March 10th
total days between the two dates - 64 days
remaining days from now until end day - 33 days
so the campaign has been running (64-33) = 31 days [totaldays-remaining days]
as such the campaign is (31/64 * 100) % complete [48%]
In your jsfiddle, you're formatting the date wrong, which returns a wrong display date.
See snippet:
console.log(moment(1583884740000).format('MMMM d YYYY'))
console.log(moment(1583884740000).format('MMMM D YYYY'))
<script src="https://unpkg.com/moment#2.24.0/min/moment.min.js"></script>
moment(1583884740000).format('MMMM D YYYY') returns 'March 11 2020' which is the correct amount of days after today.
In your line with days remaining, you are using the current date instead of your first date. moment() will return the current date and time.
m[2] = ["days remaining", moment(1583884740000).diff(moment(), 'days')];
Put your first timestamp in and the result will be 27 days remaining, which is correct.
m[2] = ["days remaining", moment(1583884740000).diff(moment(1581465600000), 'days')];
Here's a working fork of your fiddle: https://jsfiddle.net/bd91mjs7/2/
To solve your text problem you could calculate your remaining days beforehand and change the text accordingly:
let daysLeft = moment(1583884740000).diff(moment(1581465600000);
let daysLeftLabel = daysLeft < 0 ? 'finished ago' : 'days remaining'
var m = [];
m[0] = ["moment(date1)", moment(1581465600000).format('MMMM D YYYY')];
m[1] = ["moment(date2)", moment(1583884740000).format('MMMM D YYYY')];
m[2] = [daysLeftLabel, Math.abs(daysLeft), 'days')];
Note: Math.abs() returns the absolute value, so that you don't get "-X days ago"
I'm not sure about the
"10 days remaining" -- it reads "finished 30 days ago"
part though, in my example it would read "days ago 10" instead of "days remaining -10". You may need to change the logic yourself there.
Update: as #nsevens stated, you are also using the wrong date format. Instead of d, which gets you the day of the week, you should use D which returns the day of the month (https://momentjs.com/docs/#/displaying/format/). I updated my example above.
This is my first time posting a question on here however I am a long term user of StackOverflow.
I am very new to Javascript and am currently trying to solve a few issues I am having on a website I am creating for my university course.
I am trying to make a little information box on the website's dashboard that simply tells you when your next rubbish bin collection day is. This is currently every 2 weeks on a Friday, the next being 1st April. I was wondering if there was a simple way for me to display the next bin collection date until it's the day of the bin collection, where the text would change to say 'bin collection today!' and after about 6pm it would change to the next collection date in a fortnight.
Sorry if this is extremely poorly worded! The website will only be used in the UK so I don't need to worry about time zones.
Any help would be very much appreciated!
Many thanks,
Emily
Below is some code to show how it might be done, hopefully there are sufficient comments.
As far as I know, some parts of the UK observe daylight saving but the following should not be affected by any change of timezone since it uses local date methods.
Any date can be used for the start of the cycle, I've chosen 10 June 2011 totally randomly. Also, any time of day can be used to change the message on the final day from "put your bins out today" to the standard "next cycle is in x days".
The algorithm is calculate the number of milliseconds to the next full fortnight from the start date by subtracting the number of milliseconds from the last full fortnight from the milliseconds per fortnight. Then the remainder is converted to full days.
To save ambiguity on the day before the cycle ends (in this case, a Thursday) the message says the cycle ends "tomorrow" rather than in 1 day, and on the day itself, up to 18:00 or 6 pm it says the cycle ends today. After that, it says the cycle ends in 14 days or less.
// Date objects are based on milliseconds (8.64e7 per day)
// Calculate milliseconds for a fortnight
var msPerFortnight = 8.64e7 * 14;
// Any date can be the start of the fortnightly cycle
// Make Friday 10 June 2011 first day of cycle,
// Cycles end on 25 March, 6 April 2016.
// Note months are zero based so June is 5
var firstDayOfCycle = new Date(2011, 5, 10);
// Time of day to stop showing "put bins out today" message on start/end day
// 18 is 6 pm
var endHour = 18;
// Get the day name for the cycle start/end
var dayName = ['Sunday','Monday','Tuesday','Wednesday','Thursday',
'Friday','Saturday'][firstDayOfCycle.getDay()];
// Convert end hour to convenient format with am/pm
var endHourNeat = (endHour % 12 || 12) + ' ' + (endHour < 12? 'am' : 'pm');
// Get a date for now
var now = new Date();
// Get milliseconds to next full fortnight by
// msPerFortnight minus milliseconds since last full fortnight
var m = msPerFortnight - ((new Date() - firstDayOfCycle) % msPerFortnight);
// Calculate time remaining full days
var daysLeft = Math.ceil(m / 8.64e7);
// Create a human friendly message
var message;
// If more then one day left, or after 18:00 on last day, show this message
if (daysLeft == 14 && now.getHours() < endHour) {
message = 'Today is ' + dayName + ', so please put your bins out before ' + endHourNeat + '!';
} else if (daysLeft > 1 ) {
message = 'Put your bins out on ' + dayName + ' in ' + daysLeft +
' day' + (daysLeft == 1?'':'s') + ' time.';
} else if (daysLeft == 1) {
message = 'Put your bins out tomorrow, on ' + dayName + '.';
}
document.write(message);
You can even add the date of the end of the cycle and add ordinal, so it might read "Put your bins out on Friday the 25th, in 3 days time". But I'll leave that up to you.
A possible solution is to use Unix epoch, because they give you your time in seconds from 1/1/1970. By using this we can find how far we are into a fortnight. I found that Math.floor(Date.parse("2016-04-01")/86400000)%14equals 8.
Then your code might be:
var days_into_fortnight=Math.floor(Date.now()/86400000)%14;
var string_to_show;
var days_to_collection;
if (days_into_fortnight==8){
string_to_show="Bin collection!";
}
else{
if(days_into_fortnight<8){
days_to_collection=8-days_into_fortnight;
}
else{
days_to_collection=22-days_into_fortnight;
}
string_to_show=days_to_collection.toString()+" day(s) to collection!";
}
Edit:spelling
The moment.js library is awesome, and I use it almost all the time, but I recently ran into something interesting. I'm trying to plot data by week of the year, and one of the data points was 2013-12-31, moment.js tells me this is week 1? Is there a better way to handle this? either with 53, null, -1, or something?
moment('2013-12-31').week()
(returns) 1
I thought maybe using isoWeek or format would get around this, but they all return the same value of 1, despite the documentation saying it goes to 53.
moment('2013-12-31').isoWeek()
(returns) 1
+moment('2013-12-31').format('w')
(returns) 1
Anyone have any ideas on this? (short of making a test whether the week computed has a min/max date that covers the date value I passed it)
It is because the week from the 30th december 2013 is considered to be the 1st week of 2014 as you may see on this page epoch converter
And according to momentjs documentation:
The week with January 1st in it is the first week of the year.
I had a problem at my work where we used .format('YYYY WW') for some comparison logic.
That doesn't really make sense, as you should probably use .format('gggg WW') in such cases.
moment('2013-12-31').format('YYYY w'); // Returns 2013 1
moment('2013-12-31').format('gggg w'); // Returns 2014 1
https://momentjs.com/docs/#/displaying/format/
This is expected behavior. According to the ISO 8601 standard, 2013 is not a year with 53 weeks.
The long years, with 53 weeks in them, can be described by any of the following equivalent definitions:
any year starting on Thursday (dominical letter D or DC) and any leap year starting on Wednesday (ED)
any year ending on Thursday (D, ED) and any leap year ending on Friday (DC)
years in which 1 January and 31 December (in common years) or either (in leap years) are Thursdays
(source)
2013 started and ended on a Tuesday so therefore it is not a "long year" and 2013-12-31 is considered part of the first week of 2014.
If you want that week to be the 53rd, you'll have to write custom code for it as the ISO standard won't agree with you!
Moment.js docs aren't that straightforward with this I had to move from WW-YYYY to WW-GGGG
moment(2019-12-30T00:20:53.380Z).format(WW-YYYY) // Gave me 01-2019 incorrectly
moment(2019-12-30T00:20:53.380Z).format(WW-GGGG) // Gave me 01-2020 correctly
Findings
If your doing locale weeks, use ww & gggg
If your doing ISO weeks, use WW & GGGG
A mix of w/W & Y is incorrect usage
I had the same problem with the calculation of the week number, starting from the date of Sunday.
Finally I was able to solve the problem by calculating the week number starting not from Sunday but from Monday.
moment(date).isoWeekday(1).week()
Better right a custom method which will convert date into week and that can be customized easily.
//value : (MMM DD YYYY format)
function getEpiWeek(value) {
Date.prototype.getWeek = function () {
var target = new Date(this.valueOf());
// ISO week date weeks start on monday, so correct the day number
var dayNr = (this.getDay() + 7) % 7;
// Set the target to the thursday of this week so the
// target date is in the right year
target.setDate(target.getDate() - dayNr + 3);
// ISO 8601 states that week 1 is the week with january 4th in it
var jan4 = new Date(target.getFullYear(), 0, 4);
// Number of days between target date and january 4th
var dayDiff = (target - jan4) / 86400000;
if (new Date(target.getFullYear(), 0, 1).getDay() < 4) {
return 1 + Math.ceil(dayDiff / 7);
}
else { // jan 4th is on the next week (so next week is week 1)
return Math.ceil(dayDiff / 7);
}
};
var weekNumber = new Date(value).getWeek()
var year = getYear(value, weekNumber);
return weekNumber + ' ' + year;
}
function getYear(value, weekNumber) {
var year = parseInt(value.split(' ')[2]);
if (value.split(' ')[0] == 'Jan') {
if (weekNumber > 40) {
year = year - 1;
}
}
if (value.split(' ')[0] == 'Dec') {
if (weekNumber < 2) {
year = year + 1;
}
}
return year.toString();
}
Personally solved my ordering issue using :
if(d.month()==0) {
week = d.week();
}else{
week=d.isoWeek();
}
I really need some assistance with a time calculation in JS.
Put basically I need to calculate how many times a day of a month has occurred between two dates.
For Example -
A date of 15th of the month between 1st February 2014 to 14 May 2014 would be 3
A date of 15th of the month between 1st February 2014 to 16 May 2014 would be 4
I've looked at moment Jquery library but it estimates that a month is 30 days so I wouldn't be exact and take into consideration leap years - months with 28 days etc..
It really needs to be exact because its for a chargeable event calculation. The dates can spare many years so could lead to in-accuries because of the 30 day thing.
Any help would be appreciated
There are probably a million ways to do this... here's a brute force way:
// add a "addDays() method to Date"
Date.prototype.addDays = function(days)
{
var dat = new Date(this.valueOf());
dat.setDate(dat.getDate() + days);
return dat;
}
// provide two dates and a day ordinal you want to count between the two
function numOrdinalsBetweenDts(Date1, Date2, theOrdinal) {
var temp;
if(Date2 < Date1) { // put dates in the right order (lesser first)
temp = Date1;
Date1 = Date2;
Date2 = temp;
}
var workDate = Date1;
var ctr = 0;
while(workDate < Date2) { // iterate through the calendar until we're past the end
if(workDate.getDate() == theOrdinal) // if we match the ordinal, count it
ctr++;
workDate = workDate.addDays(1); // move the calendar forward a day
}
return ctr;
}
var result = numOrdinalsBetweenDts(new Date("July 21, 1901"), new Date("July 21, 2014"), 2);
console.log(result);
alert(result);
There is a slightly counter-intuitive behavior in the Javascript Date constructor where if you create a new Date with the day set to 0, it will assume the last day of the month. You can the use the following function get the number of days in a month:
function daysInMonth(month, year) {
return new Date(year, month, 0).getDate();
}
The Javascript date object is leap-year aware, so you can use this function reliably.
You then just need to count the number of months between the start and end date and check each one to make sure the day number is actually present in the month. You can short-circuit this check if the day is less than or equal to 28.
I have a validator that checks if an user is at least 18 years old.
This is the check:
var res = /^([1-2]\d{3})\-(0[1-9]|1[012])\-(0[1-9]|[12][0-9]|3[01])\-([0-9]{4})$/.exec(str);
var todays_date = new Date();
var birth_date = null;
if (res != null) {
birth_date = new Date(res[1], res[2], res[3]);
if (todays_date - birth_date > 565633905872) {
565633905872 is 18 years in milliseconds but how do I convert it to years before so I can just do:
if (todays_date - birth_date => 18) {
The number you have quoted is not the number of milliseconds in 18 years. It's too small even if you pretend there are no leap years.
The simplest way to test if somebody is at least 18 years old is to initialise a date object to their birthday, then use .getFullYear() and .setFullYear() to directly set the year 18 years forward. Then compare that with the current date.
Note also that in JS dates the month is zero-based, so you probably want to use res[2] - 1 when creating the date object.
birth_date = new Date(res[1], res[2] - 1, res[3]);
birth_date.setFullYear(birth_date.getFullYear() + 18);
if (birth_date <= new Date()) {
Or given you are constructing the birth_date from individual year, month and day you could just do:
birthPlus18 = new Date(+res[1] + 18, res[2] - 1, res[3]);
if (birthPlus18 <= new Date()) {
(The leading + in +res[1] + 18 is not a typo, it converts the string extracted by your regex into a number so that you can add 18 to it. You don't need to do the same thing for res[2] - 1 because - automatically converts both operands.)
Note also that your regex will happily allow dates that specify a day that is too high for the month, e.g., Feb 30 or Jun 31.
There are better ways of checking this (see the answer of "nnnnnn"). But your question wasn't about a better way but, how you could convert to years.
You could write a function that does that, example:
function convertmili( mSeconds )
{
return mSeconds / 31536000000;
}
The output of this function is still far from ideal, because your example would output: 17.9361334941654
So we could clean it up a bit:
function convertmili( mSeconds )
{
var checkYear = Math.floor(mSeconds / 31536000000);
return checkYear;
}
With this function, your example would output 17 and then you can check it the way you wanted.
Divide your millisecond value by 31536000000 you get number of years
http://www.convertunits.com/from/milliseconds/to/year