Extract zone offset from a moment's date - momentjs

I need to build a function that receives a string with a date and I need to extract the time offset.
var moment = require('moment');
function extractZoneOffset(date){
...
}
extractZoneOffset("2015-12-11 00:00:00-03:00") // -3
extractZoneOffset("2015-12-11 00:00:00-04:00") // -4
extractZoneOffset("2015-12-11 00:00:00Z") // 0
extractZoneOffset("2015-12-11 00:00:00-05:00") // -5
I can't find a function to extract the timezone neither in moment's docs nor in moment-timezone's docs

Related

How to create a momentJS object with a specfic time and a specific timezone(other than the default local time zone)?

I will receive an string(with time and date) from the frontend. The string format is this "2021-08-16T23:15:00.000Z". I intend to declare a moment object with the input string, along with a specific timezone(other than the local one).
import moment from "moment";
import "moment-timezone";
// The input string I receive from the frontend.
let strTime = "2021-08-16T23:15:00.000Z";
console.log(strTime); //2021-08-16T23:15:00.000Z
let time = moment.tz(strTime, "YYYY-MM-DDTHH:mm:ss.SSSZ","America/Boise");
console.log(time); // Moment<2021-08-16T17:15:00-06:00>, undesired value
let UTCtime = moment.utc(time);
console.log(UTCtime);
As far as what I understood from this question, console.log(time) should output a moment object of time 23:15:00, but with timezone "America/Boise".
What I intend is time to have the same time i.e "23:15:00.000", with "America/Boise" as timezone.
So that when I later convert that time to UTC, I need to get the right value w.r.t the timezone "America/Boise" and not my local timezone. How can I do this.
I figured out a solution.
const momenttz = require("moment-timezone");
const moment = require("moment");
// The input string I receive from the frontend.
let strTime = "2021-08-16T23:15:00.000Z";
console.log(strTime); //2021-08-16T23:15:00.000Z
let time = moment.utc(strTime);
time.tz("America/Boise", true);
console.log(time.tz());
console.log(time); // Moment<2021-08-16T23:15:00-06:00>, desired value
let UTCtime = moment.utc(time);
console.log(UTCtime); // Moment<2021-08-17T05:15:00Z>
In the above code, at console.log(time),time has the value "23:15:00.000" with required timezone "America/Boise". This makes it possible for you to get the right value , when you later convert it to UTC.
This is made possible by passing an optional second parameter to .tz mutator of moment-timezone as true which changes only the timezone (and its corresponding offset), and does not affect the time value.
time.tz(timezone, true);
A sample example of using this is given in the answer code above.
You can read more about it here in the Moment Timezone Documentation

Moment.js, FullCalendar.js datetime comparisons with timezone offsets

I'm confused.
I have a textbox that is populated with a date and time (string) such as '09/07/2021 10:30'.
I convert this string to a moment like so:
var suggestedDateObj = moment(suggestedDate, 'DD/MM/YYYY HH:mm');
I then want to check if this date and time is in between time slots in a fullcalendar.js event object. I do this like so:
var startDateObj = moment(value.start);
var endDateObj = moment(value.end);
if (suggestedDateObj.isBetween(startDateObj, endDateObj)) {}
However...it isn't working. And it's due to timezone offset (i think).
suggestedDateObj returns a value with a UTC offset of +0100 (British Summer Time)
However my calendar event objects return a date with a UTC offset of +0000. So when i check if '09/07/2021 10:30 +0100' is in between '09/07/2021 10:30 +0000' and '09/07/2021 11:30 +0000' it doesn't work!
I guess my question is really either:
How can I create my suggestedDateObj moment with a timezone offset of zero? OR
How can i tell fullcallendar events that the time it is displaying is actually BST (+0100)? At the moment I don't specify the 'Timezone' parameter.
Thanks.
UPDATE
Hmm....this might work....although it feels a bit clunky:
var tmoment1 = moment(suggestedDate, 'DD/MM/YYYY HH:mm');
//create default date with specific timezone offset of zero
var suggestedDateObj = moment().utcOffset(0);
//set the date and time
suggestedDateObj.set({
day: tmoment1.day(),
month: tmoment1.month(),
year: tmoment1.year(),
hour: tmoment1.hour(),
minute: tmoment1.minute(),
second: 0
});
You can generate suggestedDateObj in utc like that:
var suggestedDateObj = moment.utc(suggestedDate, 'DD/MM/YYYY HH:mm');`
For the .isBetween() I suggest you to use the square bracket like forth parameter, like documentation says.
if (suggestedDateObj.isBetween(startDateObj, endDateObj, undefined, '[]'))
The square brackets indicate that the check must include the dates of the limiter

Zero-based formatting for week moment.js is not available

So I am pulling in a date from MySQL db.
I receive date of "2020-00" for example
I need to compare that to a moment formatted string but moment starts at 1 instead of zero.
How can I use moment to use zero-based formatting?
Bottomline is that I am comparing "2020-01" to "2020-00"
const moment = require('moment');
const string = "2020-01-01"
let tzdate = moment("2020-01-01T00:00:00.000Z")
tzdata = tzdate.format('YYYY-ww');
console.log(tzdata)

Wrong date difference calculated using momentjs

I am trying to calculate the number of days between two dates using moment js.
function (value) {
var expiration= moment(value).format('DDMMYYYY');
var today = moment().format('DDMMYYYY');
var dayToExpiration = moment(expiration- today).format('D[days] ,H[hours]');
console.log(today + " : " + expiration
console.log(dayToExpiration);
The result is:
11102018 : 28102020 //--> 11.10.2018 : 28.10.2018
1 days ,6 hours //why only one day??
Because your dayToExpiration variable should be a moment.Duration object, not a string.
The difference between two datetimes is a duration, not a datetime.
Short answer:
As John Madhavan-Reese stated in his answer, you have to use moment Duration to represent the diffecence between two moments in time.
Issue in the code sample:
In your code you are creating a moment object from the difference between expiration and today. This value is interpreded by moment as the number of milliseconds since the Unix Epoch (see moment(Number)), so you are creating a moment object for a random day around the 1st January 1970 (see the output of moment(expiration- today).format() ). The D token in format() stands for Day of Month, so it gives an "incorrect" output.
My suggested solution:
You can calculate difference using momentjs' diff() then you can create a duration using moment.duration(Number).
Finally you can get your desired output using moment-duration-format plug-in (by John Madhavan-Reese :D)
Here a live sample:
function getDiff(value) {
var expiration= moment(value); // Parse input as momement object
var today = moment(); // get now value (includes current time)
// Calculate diff, create a duration and format it
var dayToExpiration = moment.duration(Math.abs(today.diff(expiration))).format('D[days], H[hours]');
console.log(today.format('DDMMYYYY') + " : " + expiration.format('DDMMYYYY'));
console.log(dayToExpiration);
}
getDiff('2018-10-28');
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.22.2/moment.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment-duration-format/2.2.2/moment-duration-format.min.js"></script>
I am getting errors. this one works for me:
moment.duration(expiration.diff(today))._milliseconds / (1000*60*60*24));

How to add minutes in moment js with a HH:mm format?

How do I add minutes to this. I followed the documentation but somehow this is not working:
var hours = randomIntFromInterval(0,23);
var minutes = randomIntFromInterval(0,59);
var time = moment(hours+':'+minutes,'HHmm').format("HH:mm");
time.add(7,'m');
Only the last line is not working, but should be right according to the documentation. What am I doing wrong?
format returns a string, you have to use add on moment object.
Your code could be like the following:
var hours = randomIntFromInterval(0,23);
var minutes = randomIntFromInterval(0,59);
var time = moment(hours+':'+minutes,'HH:mm');
time.add(7,'m');
console.log(time.format("HH:mm"));
Note that you can create a moment object using moment(Object) method instead of parsing a string, in your case:
moment({hours: hours, minutes: minutes});
As the docs says:
Omitted units default to 0 or the current date, month, and year
You can use IF condition to see if minutes < 10
to add "0" like 07,08
var d = new Date()
var n = d.getMinutes()
if(n<10)
n="0"+n;
But watch out you will have to slice that zero if you want to increment.

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