Datetime with Moment.js javascript

Lib:  https://momentjs.com/

Date Formatting

Using Moment.js to format daté and times helps you write code simpler and much easier.

The simple example is as follows:

moment().format('YYYY MM DD');  // current date time have format YYYY MM DD
moment("2017-01-01").format("DD MMM YYYY") // 01 Jan 2017 

The format of date times, you can find more in the docs của moment.js.

Date Validation

Use moment.js to confirm that the date time entered is in the correct format as date time. 

Using the isValid () method, returns true / false.

moment("2010 13",           "YYYY MM").isValid();     // false (invalid month)
moment("2010 11 31",        "YYYY MM DD").isValid();  // false (invalid day)
moment("2010 2 29",         "YYYY MM DD").isValid();  // false (not is leap year)
moment("2010 notamonth 29", "YYYY MMM DD").isValid(); // false (invalid name of the month)

Some note that the moment.js parser is quite forgiving :), even if it analyzes that a certain word in the date time is correct, it will return isValid () to true.

moment('2016 is a date', 'YYYY-MM-DD').isValid() //true, 2016 was matched
moment('It is 2012-05-25', 'YYYY-MM-DD').isValid(); // true 2012-05-25 matched

If you need the parser of the moment more closely, you must add the boolean as the final argument.

moment('It is 2012-05-25', 'YYYY-MM-DD').isValid();       // true
moment('It is 2012-05-25', 'YYYY-MM-DD', true).isValid(); // false
moment('2012-05-25',       'YYYY-MM-DD', true).isValid(); // true
moment('2012.05.25',       'YYYY-MM-DD', true).isValid(); // false

To know where it is invalid, you can use the function invalidAt () as follows:

moment("2014-14-01").invalidAt();  // 1 => month
moment("2014-01-32").invalidAt(); // 2 => day

Its return value:

1: years
2: months
3: days
4: hours
5: minutes
6: seconds
7: milliseconds

Manipulating Dates

Add

moment().add(Number, String);
moment().add(Duration);
moment().add(Object);

ví dụ:

moment (), add (7, 'days'); // Returns an object that has a date time of 7 days
moment (). add (7, 'd'); / acronym as above

Key	Shorthand
years	y
quarters	Q
months	M
weeks	w
days	d
hours	h
minutes	m
seconds	s
milliseconds	ms

moment().add(7, 'days').add(1, 'months'); // with chaining

Subtract

moment().subtract(Number, String);
moment().subtract(Duration);
moment().subtract(Object);

Ex:

moment().subtract(7, 'days');

Start of Time

moment().startOf('year');    // set to January 1st, 12:00 am this year
moment().startOf('month');   // set to the first of this month, 12:00 am
moment().startOf('quarter');  // set to the beginning of the current quarter, 1st day of months, 12:00 am
moment().startOf('week');    // set to the first day of this week, 12:00 am
moment().startOf('isoWeek'); // set to the first day of this week according to ISO 8601, 12:00 am
moment().startOf('day');     // set to 12:00 am today
moment().startOf('date');     // set to 12:00 am today
moment().startOf('hour');    // set to now, but with 0 mins, 0 secs, and 0 ms
moment().startOf('minute');  // set to now, but with 0 seconds and 0 milliseconds
moment().startOf('second');  // same as moment().milliseconds(0);

End of Time

moment().endOf("year"); // set the moment to 12-31 23:59:59.999 this year

Time from now

moment().fromNow();   // time ago
moment().fromNow(Boolean); // relative time

moment("2012-01-01").fromNow(); // 6 years ago
moment("2012-01-01").fromNow(true); // 6 years

Time from X

moment().from(Moment|String|Number|Date|Array);
moment().from(Moment|String|Number|Date|Array, Boolean);

var a = moment([2007, 0, 28]);  // can write array or string
var b = moment([2007, 0, 29]); / can write array or string
a.from(b) // "a day ago"

Difference

var a = moment([2007, 0, 29]);
var b = moment([2007, 0, 28]);
a.diff(b, 'days') // 1

Days in Month

moment("2012-02", "YYYY-MM").daysInMonth() // 29
moment("2012-01", "YYYY-MM").daysInMonth() // 31

Is Leap Year

Check is leap year

moment([2000]).isLeapYear() // true
moment([2001]).isLeapYear() // false
moment([2100]).isLeapYear() // false

Get

moment().get('year');
moment().get('month');  // 0 to 11
moment().get('date');
moment().get('hour');
moment().get('minute');
moment().get('second');
moment().get('millisecond');

Conclusion

Using the Moment.js library, manipulating and working with day time will no longer be a problem.

These are just concepts and methods that are important and often use the time, but there are many other methods you can refer to at Moment.js.

https://www.sitepoint.com/managing-dates-times-using-moment-js/
https://momentjs.com/docs/