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How do I get the days between the today's day and the last day of the month using Moment.js?

Here's the code that I have right now:
const moment = require('moment')
const m = moment
const currDay = m().format('D')
const dayOfWeek = m().format('dddd')
const daysInMonth = m().daysInMonth()
const startOfMonth = moment().startOf('month').format('YYYY-MM-DD hh:mm');
const endOfMonth = moment().endOf('month').format('YYYY-MM-DD hh:mm');
I need to create a calendar row where the first item would be the todays date, and the rest of the calendar items would be the whatever amount of days are left depending on the current month so I could render each day in between in my HTML with Vue.
Example: Wed 8, Thu 9, Fri 10 ... Fri 31.

I think the OP is tripped up on the common mistake of formatting prematurely. format is good to see an intermediate result, but doing so produces a string that's no good for additional calculation.
Try to handle date objects only. Convert to strings only when you must: (a) presenting to a human reader, or (b) serializing for storage or transmission.
Working without formatting...
const daysRemainingThisMonth = moment().endOf('month').diff(moment(), 'days');
console.log(`There are ${daysRemainingThisMonth} days remaining this month`)
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.29.1/moment.min.js"></script>

Just as a POJS equivalent, if you have a function to return the last day of the month, you can use that and just get the difference between the two dates, e.g.
function getMonthEnd(date = new Date()) {
return new Date(date.getFullYear(), date.getMonth() + 1, 0);
}
function getMonthDaysLeft(date = new Date()) {
return getMonthEnd(date).getDate() - date.getDate();
}
let d = new Date();
console.log(`There are ${getMonthDaysLeft(d)} days left in ${d.toLocaleString('en',{month:'long'})}.`);
To get a list/array of the days remaining, just loop over a date, adding 1 day at a time, and write the dates in the required format into the list:
function getMonthDaysLeftAsList(date = new Date()) {
let d = new Date(+date);
// Formatter
let f = new Intl.DateTimeFormat('en',{
day: 'numeric',
month: 'short'
});
let m = d.getMonth();
let dayList = [];
while (d.getMonth() == m) {
dayList.push(f.format(d));
d.setDate(d.getDate() + 1);
}
return dayList;
}
console.log(getMonthDaysLeftAsList());

How to convert this date into actual date

So this is a new one to me. I've been working with this api and they returned a date in json format that looks like this
{
DateAdd: "/Date(1582936941390-0600)/"
}
not exactly sure how to convert this to a datetime like in the format below so I can actually do something with it.
2020-03-13 23:08:00
i have never seen this date format before! Thanks

Use moment.js to convert the date format
var data = {
DateAdd: "/Date(1582936941390-0600)/"
}
var datam = moment(data.DateAdd)
console.log(datam.format("YYYY-MM-DD HH:mm:ss")) // 2020-02-29 07:42:21
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.24.0/moment-with-locales.min.js"></script>

If you don't care about the timezone, you can just cut the timestamp out of that string:
const dateString = data.DateAdd;
const date = new Date(Number(dateString.match(/\d+/)[0]));

You can convert date into desired format by Javascript date object.
let addZero = (i) => {
if (i < 10) {
i = "0" + i;
}
return i;
}
let formatDate = (date) => {
let year = date.getFullYear(),
month = addZero(date.getMonth() + 1),
day = addZero(date.getDate() + 1),
hours = addZero(date.getHours() + 1),
minutes = addZero(date.getMinutes() + 1),
seconds = addZero(date.getSeconds() + 1);
let dateArr = [year, month, day];
let timeArr = [hours, minutes, seconds];
let result = dateArr.join('-').concat(" ", timeArr.join(':'));
return result;
}
let inputString = "/Date(1582936941390-0600)/";
let inputData = new Date(Number(inputString.match(/\d+/)[0]));
console.log(formatDate(inputData));
Please read more about Javascript date object

Date calculation using javaScript

I need date algorithms, Which will display me how long I have been given a date anywhere.
Example:
Suppose
Today is 01/06/2019 (dd/mm/yy)
BirthDate is 31/05/2019 (dd/mm/yy)
Now, My age is 1 day 0 Months and 0 years
[NOTE: I need all of them, It means day/month and years]
I have been read at least 23 articles/post in this site but they only give years or month or date but not everything in one...
var date, cDate, cMonth, cYears, oDate, oMonth, oYears;
date = new Date()
//current date
cDate = date.getDate()
cMonth = date.getMonth()
cYears = date.getFullYear()
//birth date
oDate = 01
oMonth = 05
oYears = 2019
(Multiplying is not the main solution I think so, need to work with all arithmetics operator)

This will give you the result you need
var birth = new Date("5/31/2019"); // mm/dd/year
var today = new Date();
var diff = today.valueOf()-birth.valueOf();
var result = new Date(diff);
var dayDiff = result.getDate() - 1; //because epoch start from 1st
var yearDiff = result.getFullYear() - 1970; //because epoch start from 1970
var str = `${dayDiff} day ${result.getMonth()} Months and ${yearDiff} years`;
console.log(str);

You should use moment, so there you can do:
var a = moment("04/09/2019 15:00:00");
var b = moment("04/09/2013 14:20:30");
console.log(a.diff(b, 'years'))
console.log(a.diff(b, 'months'))
console.log(a.diff(b, 'days'))
Similarly, you can get minutes, hours and seconds if you need.
While using the library moment.js

Javascript: formatting a date [duplicate]

This question already has answers here:
Where can I find documentation on formatting a date in JavaScript?
(39 answers)
Closed 4 years ago.
I want to the current date/time formatted in this format:
year+'-'+month+'-'+day+' '+hour+':'+minute+':'+second+':'+milli;
Currently I'm doing it as such. Is there a more elegant approach without the use of external libraries like moment.js?
var now = new Date();
var year = now.getFullYear();
var month = now.getMonth()+1;
var day = now.getDate();
var hour = now.getHours();
var minute = now.getMinutes();
var second = now.getSeconds();
var milli = now.getMilliseconds();
if(month.toString().length == 1) {
var month = '0'+month;
}
if(day.toString().length == 1) {
var day = '0'+day;
}
if(hour.toString().length == 1) {
var hour = '0'+hour;
}
if(minute.toString().length == 1) {
var minute = '0'+minute;
}
if(second.toString().length == 1) {
var second = '0'+second;
}
if(milli.toString().length == 1) {
var milli = '0'+milli;
}
var m_session_startTime = year+'-'+month+'-'+day+' '+hour+':'+minute+':'+second+':'+milli;

Leverage template literals instead of concatenation and padStart() to fill leading zeros.
const now = new Date();
const year = now.getFullYear();
const month = String(now.getMonth() + 1).padStart(2, "0");
const day = String(now.getDate()).padStart(2, "0");
const hour = String(now.getHours()).padStart(2, "0");
const minute = String(now.getMinutes()).padStart(2, "0");
const second = String(now.getSeconds()).padStart(2, "0");
const milli = String(now.getMilliseconds()).padStart(4, "0");
const m_session_startTime = `${year}-${month}-${day} ${hour}:${minute}:${second}:${milli}`;
console.log(m_session_startTime);

You could use moment.js, it really helps you with formatting dates.
console.log(moment().format('YYYY-MMMM-DD h:mm:ss:SSS'));
<script src="https://momentjs.com/downloads/moment.min.js"></script>
This command does the job pretty well. moment() is a date object, when there are no arguments given like in this example it takes the current time but you can also use moment("2018-12-4") for specific dates.
You can then format the date according to your need,
YYYY is the full year (2018)
MMMM is the full month name (July)
(you can also use MMM for the short version of the month name)
DD is the day as a number (24)
(you can also use dddd for the full name of the day or ddd for the short name)
h is the hour as number (22)
mm is the minute as a number (23)
ss is the second as a number (as an example 22)
SSS is the millisecond as a number (example 245)

Try this?
let date = new Date();
let jsonDate = date.toJSON();
jsonDate = jsonDate.replace(/[TZ]/g, " ");
jsonDate = jsonDate.replace(/\./g, ":");
console.log(jsonDate);
> 2018-07-24 20:32:06:435
Alternatively, if you want to split the entire thing into substrings:
let date = new Date();
let jsonDate = date.toJSON();
jsonDate = jsonDate.replace(/[TZ]/g, " ");
jsonDate = jsonDate.replace(/\./g, ":");
let dateTime = jsonDate.split(" ");
let dt = dateTime[0].split("-");
let tt = dateTime[1].split(":");
let year = dt[0];
let month = dt[1];
let day = dt[2];
let hour = tt[0];
let minute = tt[1];
let second = tt[2];
let mili = tt[3];
console.log(jsonDate);
console.log(dateTime[0]);
console.log(dateTime[1]);
console.log([year, month, day, hour, minute, second, mili].join("~"));
console.log("Date: " + [year, month, day].join("-") + " Time: " + [hour, minute, second, mili].join(":"));
> 2018-07-24 21:03:05:706
> 2018-07-24
> 21:03:05:706
> 2018~07~24~21~03~05~706
> Date: 2018-07-24 Time: 21:03:05:706
As you might have noticed from this response, I work with databases. I have heavy bash, javascript, php, sql, golang background.

Use a moment.js. Great library that is designed to exactly what you would like. You can use the .format option.
var now = moment().format('YYYY-MM-DD HH:mm:ss.SSS');
$('#timeval').text(now);
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
Current Time: <br>
<a id="timeval"></a>
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.22.2/moment.min.js"></script>
https://momentjs.com/

How to convert timestamp to readable date/time?

I have an API result giving out timestamp like this 1447804800000. How do I convert this to a readable format using Javascript/jQuery?

You can convert this to a readable date using new Date() method
if you have a specific date stamp, you can get the corresponding date time format by the following method
var date = new Date(timeStamp);
in your case
var date = new Date(1447804800000);
this will return
Wed Nov 18 2015 05:30:00 GMT+0530 (India Standard Time)

Call This function and pass your date :
JS :
function getDateFormat(date) {
var d = new Date(date),
month = '' + (d.getMonth() + 1),
day = '' + d.getDate(),
year = d.getFullYear();
if (month.length < 2)
month = '0' + month;
if (day.length < 2)
day = '0' + day;
var date = new Date();
date.toLocaleDateString();
return [day, month, year].join('-');
}
;

In my case, the REST API returned timestamp with decimal. Below code snippet example worked for me.
var ts= 1551246342.000100; // say this is the format for decimal timestamp.
var dt = new Date(ts * 1000);
alert(dt.toLocaleString()); // 2/27/2019, 12:45:42 AM this for displayed