Moment js: moment(0) = Wed Dec 31 1969? - javascript

I tried to make null date.
so I tried to make them all 0 when I click the clear button.
this.clear = function () {
_this.newQuarters.forEach(function (_value, index) {
_value.startDate = 0;
_value.endDate = 0;
_value.suppressAllocation = false;
_value.quarters.forEach(function (_childValue, index) {
_childValue.startDate = 0;
_childValue.endDate = 0;
_childValue.suppressAllocation = false;
});
});
};
}
After that, I tried to add 0 at moment from other function.
this.newQuarters.forEach(function (_value, index) {
var startDate = moment(_value.startDate);
but, it display startDate = Wed Dec 31 1969.
Please help me to find to make all date are null.

When passing a number to the moment() function, it interpret it as a unix timestamp.
Which is the number of second since EPOCH time, or 01-01-1970.
So passing 0 to that function result in the very first second of jan 1 1970. As Bergi pointed out, you are probably displaying your dates in your local timezone, which could result in a time before 01-01-1970.
If you want to create a null date, you should set your startDate to null and handle it correctly ( with an if statement).
You could also set the date back to the current time by passing no argument to the moment() function.

Dates can be tricky to work with in an application. There is no such thing as time that is not time. At least not in the world of programming. For this reason we have to create our own understanding of what a lack of time will be.
There is no time without time but there is a lack of value.
You obviously understand this, you had an approach, in your case, you seem to be fine with simply having time be zero, it just broke when working with moment as moment is using EPOCH time. Thus, zero is time.
You are going to have to test like the rest of us.
this.newQuarters.forEach(function (_value, index) {
var startDate = _value.startDate ? moment(_value.startDate) : null;
Lack of time could be whatever you want, undefine, null, a beginning date
Be consistent: Database vendors and languages handle things differently, front end is not always the same time zone, etc.

If you are dealing with momentjs library, there is a function: invalid()
You can easily make your variables invalid moment object and control their validity.
let currentDate = moment(); // Valid moment object
console.log(currentDate.format());
// make the moment object invalid
currentDate = moment.invalid();
console.log(currentDate.isValid()); // Check validity
console.log(currentDate.format()); // Invalid date
// make the moment object valid again
currentDate = moment();
console.log(currentDate.isValid()); // Check validity
console.log(currentDate.format()); // A valid date
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.24.0/moment.min.js"></script>

Related

Date Range is starting with Plus

I have created a small function which give all dates between two dates.
but this is starting from Plus 1 date.
Here's my code (also on Here is jsfiddle):
function DateRangeArr(to, from) {
console.log(to);
console.log(from);
var Dateresult = [];
var end = new Date(from);
var loop = new Date(to);
while (loop <= end) {
Dateresult.push({ 'total': 0, 'log_date': loop });
var newDate = loop.setDate(loop.getUTCDate() + 1);
loop = new Date(newDate);
}
return Dateresult;
}
console.log(DateRangeArr('2020-12-05','2020-12-12'));
It's giving me results starting from 2020-12-06 to 2020-12-13. Also will it gives result depending upon user time zone ?
There are a couple of things going on that could account for the problem.
(This is probably the thing you're seeing) You're changing the state of the Date instance that you added to the array after adding it. That changes the instance that's in the array.
Since "2020-12-05" is a date-only string, it's parsed as UTC in specification-compliant browsers (see the rules at Date.parse), so the Date objects will represent midnight on that date UTC rather than midnight on that date in your local timezone. If you want them to reliably be midnight local time, add T00:00 to the string. If you want them to be parsed reliably as UTC, you should be able to use them as-is, but the spec moved around on this (ES2015 said they should be parsed as local time, not UTC, before being updated by ES2016) so to get UTC reliably, add T00:00Z to it. (My understanding is that the spec allows just adding a Z, but others read the spec differently, and both Safari's JavaScriptCore and Firefox's SpiderMonkey reject new Date("2020-12-05Z"), so add T00:00Z.) Or use new Date(Date.UTC(year, month - 1, day)) instead.
You're mixing up accessors here: loop.setDate(loop.getUTCDate() + 1). That's using the UTC accessor to get the date, but then the local time accessor to set it. You need to be consistent in order to add a day to the date.
You haven't said how you're using the resulting array of Date objects, but just note that the date they show may seem off if (for instance) you parse them as UTC but then display the result in local time or vice-versa, because of the time zone offset.
You have to and from reversed in your code. You're using them consistently, but it's quite hard to read. :-) When building an array in date order, it goes from the earlier date to the later date.
Here's a version updated to work entirely in UTC; the resulting Date objects represent midnight UTC on each of the dates:
function dateRangeArr(from, to) {
console.log(from);
console.log(to);
var dates = [];
var end = new Date(to + "T00:00Z");
var loop = new Date(from + "T00:00Z");
while (loop <= end) {
dates.push({ "total": 0, "log_date": new Date(+loop) });
loop.setUTCDate(loop.getUTCDate() + 1);
}
return dates;
}
console.log(dateRangeArr("2020-12-05","2020-12-12"));
(I've also updated the function and variable names to be more consistent with standard practice in JavaScript, since the function isn't a constructor function.)
Here's a version that works in local time instead:
function dateRangeArr(from, to) {
console.log(from);
console.log(to);
var dates = [];
var end = new Date(to + "T00:00");
var loop = new Date(from + "T00:00");
while (loop <= end) {
dates.push({ "total": 0, "log_date": new Date(+loop) });
loop.setDate(loop.getDate() + 1);
}
return dates;
}
console.log(dateRangeArr("2020-12-05","2020-12-12"));
Which you use depends on whether you want the Date instances to represent midnight UTC (use the UTC version) or midnight local time (use the local time version).

Checking current time between two timing using moment

I am using isBetween function of moment to check if time is in an interval or not.
var currenttime = moment()
var endTime = moment(slotsTime.time, 'HH:mm').add(parseInt(slotsTime.duration), 'minutes');
var startTime = moment(slotsTime.time, 'HH:mm');
if (currenttime.isBetween(startTime, endTime)) {
console.log('dddd', slotsTime.date);
}
But every time the condition is false. I searched hundred times, found similar solutions.
Please help me out!
This should fix your problem
if (currenttime.isBetween(startTime, endTime, null, '[]')) {
console.log('dddd', slotsTime.date);
}
That tells momentjs isBetween function to include the start and end time as boundaries
The default of isBetween function does not include the start time, meaning if currentTime is exactly the start time (which in mm:hh format it is) it will return false.

How to get correct timestamp value in nodejs?

In my project my scheduling to post in social network sites using cron job,
timestamp value should end with zero instead of 1.
here is the node js code used:
var rule = new cron.RecurrenceRule();
rule.second = 0;
cron.scheduleJob(rule, function(){
var now = new Date();
var date = dateFormat(now, "dd-mm-yyyy, h:MM:ss TT");
console.log(Math.floor(new Date()/ 1000));
retrivepost(Math.floor(new Date()/ 1000).toString());
});
here is the timestamp value output log which i get in terminal
1517894101
1517894161
1517894221
1517894281
1517894341
1517894401
1517894461
1517894521
1517894581
1517894641
1517894701
1517894761
1517894821
1517894881
1517894941
1517895001
1517895061
1517895121
For me your code works just fine and logs timestamps ending with the zero second just like scheduled.
However, I think if your retrievepost() function depends on a timestamp being on the minute exactly you should round your date inside the .scheduleJob function to the nearest minute. A whole second later seems odd to me but imagine that you have some code just above that takes a while to compute. retrievepost() will fail then, even if you get it working right now.

Server-Side and Time-Specific script execution

I have a list of dates in an array(for now we can say that the dates are sorted). I want to have a script execute when the date matches a date in the array. My issue is figuring how to make this work on its own. I would like to have a server somehow act like an alarm clock that can run a script for a scheduled date and time. If anyone could help with suggestions to make this work I would appreciate it.
set date >>> if (currentDate == set date) >>> run script for the respective data
Please ask if you need clarification.
The way to do this with parse is a class with a date attribute. Create one object per date in your array of dates (they needn't be sorted).
Create a scheduled job that upon running, query's the class for the first date equal to the current date. If one is found, do whatever you want to do when an alarm is triggered.
So, something like...
Parse.Cloud.job("checkStatus", function(request, status) {
var today = new Date();
today.setHours(0, 0, 0, 0);
var tomorrow = new Date(today);
tomorrow.setDate(tomorrow.getDate() + 1);
var query = new Parse.Query("MyAlarmClass");
query.greaterThanOrEqualTo('theDateAttribute', today);
query.lessThan('theDateAttribute', tomorrow);
return query.first().then(function(anAlarm) {
if (anAlarm) {
// do whatever should be done on the alarm
} else {
// do nothing
}
}).then(function() {
status.success();
}, function(error) {
status.error(JSON.stringify(error));
});
});
Schedule this to run at least twice per day (or faster than whatever resolution you need on the alarms).

Add a duration to a moment (moment.js)

Moment version: 2.0.0
After reading the docs, I thought this would be straight-forward (Chrome console):
var timestring1 = "2013-05-09T00:00:00Z";
var timestring2 = "2013-05-09T02:00:00Z";
var startdate = moment(timestring1);
var expected_enddate = moment(timestring2);
var returned_endate = startdate.add(moment.duration(2, 'hours'));
returned_endate == expected_enddate // false
returned_endate // Moment {_i: "2013-05-09T00:00:00Z", _f: "YYYY-MM-DDTHH:mm:ss Z", _l: undefined, _isUTC: false, _a: Array[7]…}
This is a trivial example, but I can't even get it to work. I feel like I'm missing something big here, but I really don't get it. Even this this doesn't seem to work:
startdate.add(2, 'hours')
// Moment {_i: "2013-05-09T00:00:00Z", _f: "YYYY-MM-DDTHH:mm:ss Z", _l: undefined, _isUTC: false, _a: Array[7]…}
Any help would be much appreciated.
Edit:
My end goal is to make an binary status chart like the one I'm working on here:
http://bl.ocks.org/phobson/5872894
As you can see, I'm currently using dummy x-values while I work through this issue.
I think you missed a key point in the documentation for .add()
Mutates the original moment by adding time.
You appear to be treating it as a function that returns the immutable result. Easy mistake to make. :)
If you use the return value, it is the same actual object as the one you started with. It's just returned as a convenience for method chaining.
You can work around this behavior by cloning the moment, as described here.
Also, you cannot just use == to test. You could format each moment to the same output and compare those, or you could just use the .isSame() method.
Your code is now:
var timestring1 = "2013-05-09T00:00:00Z";
var timestring2 = "2013-05-09T02:00:00Z";
var startdate = moment(timestring1);
var expected_enddate = moment(timestring2);
var returned_endate = moment(startdate).add(2, 'hours'); // see the cloning?
returned_endate.isSame(expected_enddate) // true
I am working on an application in which we track live route. Passenger wants to show current position of driver and the expected arrival time to reach at his/her location. So I need to add some duration into current time.
So I found the below mentioned way to do the same.
We can add any duration(hour,minutes and seconds) in our current time by moment:
var travelTime = moment().add(642, 'seconds').format('hh:mm A');// it will add 642 seconds in the current time and will give time in 03:35 PM format
var travelTime = moment().add(11, 'minutes').format('hh:mm A');// it will add 11 mins in the current time and will give time in 03:35 PM format; can use m or minutes
var travelTime = moment().add(2, 'hours').format('hh:mm A');// it will add 2 hours in the current time and will give time in 03:35 PM format
It fulfills my requirement. May be it can help you.
For people having a startTime (like 12h:30:30) and a duration (value in minutes like 120), you can guess the endTime like so:
const startTime = '12:30:00';
const durationInMinutes = '120';
const endTime = moment(startTime, 'HH:mm:ss').add(durationInMinutes, 'minutes').format('HH:mm');
// endTime is equal to "14:30"

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