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JavaScript is partly an object-oriented language.

To learn JavaScript, we got to learn the object-oriented parts of JavaScript.

In this article, we’ll look at the Date object.

Date

The Date constructor lets us create date objects.

We can create a new Date instance by passing in nothing, a date string, values for day, month, time, etc., or a timestamp.

For instance, to create the date with the current date, we can write:

new Date();

Also, we can pass in a date string:

new Date('2020 1 1');

and we get:

Wed Jan 01 2020 00:00:00 GMT-0800 (Pacific Standard Time)

or:

new Date('1 1 2020');

and we get:

Wed Jan 01 2020 00:00:00 GMT-0800 (Pacific Standard Time)

Or:

new Date('1 jan 2020');

and we get:

Wed Jan 01 2020 00:00:00 GMT-0800 (Pacific Standard Time)

The Date constructor can figure out the date from different strings.

We can also pass in numeric values to the the Date constructor to represent the:

• year
• month, with 0 representing January to 11 for December
• day — 1 to 31
• hour — 0 to 23
• minutes — 0 to 59
• seconds — 0 to 59
• milliseconds — 0 to 999

For example, we can write:

new Date(2020, 0, 1, 17, 05, 03, 120);

And we get:

Wed Jan 01 2020 17:05:03 GMT-0800 (Pacific Standard Time)

If we pass in a number that’s out of range, it’ll be adjusted to be in range.

For instance, if we have:

new Date(2020, 11, 32, 17, 05, 03, 120);

Then we get:

Fri Jan 01 2021 17:05:03 GMT-0800 (Pacific Standard Time)

We can also pass in a timestamp.

For instance, we can write:

new Date(1557027200000);

And we get:

Sat May 04 2019 20:33:20 GMT-0700 (Pacific Daylight Time)

If we called Date without new , then we get a string representing the current date.

It doesn’t matter whether we pass in the parameters.

So if we have:

Date();

We get:

"Mon Aug 03 2020 15:02:32 GMT-0700 (Pacific Daylight Time)"

Date Methods

We can adjust the date with some instance methods.

For instance, we can use getMonth(), setMonth(), getHours(), setHours(), etc. to set the parts of a date.

To return a string, we call toString :

const d = new Date(2020, 1, 1);  
d.toString();

Then we get:

"Sat Feb 01 2020 00:00:00 GMT-0800 (Pacific Standard Time)"

To set the month, we call setMonth :

d.setMonth(2)

This returns the new timestamp:

1583049600000

To get a human-readable date, we can call toString :

d.toString();

and get:

"Sun Mar 01 2020 00:00:00 GMT-0800 (Pacific Standard Time)"

We can get the timestamp of a date with Date.UTC :

Date.UTC(2029, 0, 1);

And we can pass that into the Date constructor:

new Date(Date.UTC(2029, 0, 1))

The now method also returns the current timestamp, so we write:

Date.now();

and we get:

1596492422408

We can do the same with valueOf or the + operator:

new Date().valueOf();  
+new Date();

and they both return the current timestamp.

Conclusion

Dates can be manipulated with the Date constructor with JavaScript.

We can convert between timestamps, date objects, and string.