Learn JavaScript with me Date object _javascript tips

This article mainly introduces the operation of date and time objects.

1. Introduce

1.1 Description

Date object that is the object of the action date and time. A Date object can operate on dates and times only through methods.

1.2 Properties

No
A Date object can operate on dates and times only through methods.

2. Constructor function

2.1 New Date (): returns the current local date and time

Parameters: None

return value:

{Date} returns a Date object that represents the local date and time.

Example:

var dt = new Date ();
Console.log (DT); => returns a Date object that represents the local date and time

2.2 new Date (milliseconds): converts the number of milliseconds to a Date object

Parameters:

①milliseconds {int}: number of milliseconds, representing the number of milliseconds to begin stacking from ' 1970/01/01 00:00:00 ' as the starting point.

Note: The time of the beginning of the seconds also add the current time zone, the Times in Beijing East 8 zone, the starting time is actually: ' 1970/01/01 08:00:00 '

return value:

{Date} returns a superimposed date object.

Example:

var dt = new Date (1000 * 60 * 1); Forward 1 minute milliseconds
console.log (DT);//=> {date}:1970/01/01 08:01:00
dt = new Date (-1000 * 60 * 1);//rewind 1 minutes of milliseconds
Console.log (DT); => {date}:1970/01/01 07:59:00

2.3 New Date (DATESTR): converts a string to a Date object

Parameters:

①datestr {string}: a string that can be converted to a Date object (can be omitted); There are two main types of strings:

1) yyyy/mm/dd HH:mm:ss (recommended): If you omit the time, the date object returned time is 00:00:00.

2) Yyyy-mm-dd HH:mm:ss: If the time is omitted, the Date object returned is 08:00:00 (plus the local time zone). If you do not omit the time, this string will fail in IE conversion!

return value:

{Date} returns a converted Date object.

Example:

var dt = new Date (' 2014/12/25 '); YYYY/MM/DD
console.log (DT);//=> {DATE}:2014/12/25 00:00:00
dt = new Date (' 2014/12/25 12:00:00 ');//yyyy/ Mm/dd HH:mm:ss
console.log (DT);//=> {DATE}:2014/12/25 12:00:00

dt = new Date (' 2014-12-25 ');//yyyy-mm-dd< C5/>console.log (DT); => {date}:2014-12-25 08:00:00 (plus the time zone of East 8)
dt = new Date (' 2014-12-25 12:00:00 ');//Yyyy-mm-dd HH:mm:ss (Note: This conversion In IE will be an error! )
console.log (DT);//=> {date}:2014-12-25 12:00:00

2.4 New Date (year, month, Opt_day, Opt_hours, Opt_minutes, Opt_seconds, opt_milliseconds): convert date To date object

Parameters:

①year {int}: year; 4 digits. such as: 1999, 2014

②month {int}: month; 2 digits. Starting from 0, 0 means January, 11 represents December.

③opt_day {int} is optional: number, 2 digits, starting from 1, 1 represents 1th.

④opt_hours {int} optional: time; 2 digits; Value 0~23.

⑤opt_minutes {int} optional: 2 digits; 0~59.

⑥opt_seconds {int} optional: seconds; 2 not digits; 0~59 value.

⑦opt_milliseconds {int} is optional: milliseconds; 0~999 value.

return value:

{Date} returns a converted Date object.

Example:

var dt = new Date (2014, 11); December 2014 (The number of months entered here is one)
console.log (DT);//=> {date}:2014/12/01 00:00:00
dt = new Date (2014, 11, 25);//201 4 year December 25
console.log (DT);//=> {DATE}:2014/12/25 00:00:00
dt = new Date (2014, 11, 25, 15, 30, 40);//December 2014 25th 15:30 40 seconds
console.log (DT);//=> {DATE}:2014/12/25 15:30:40
dt = new Date (2014, 12, 25);//March 25, 2014 (This is lost The number of months entered is 12, which represents the 13th month, and jumps to the second year of January)
console.log (DT);//=> {DATE}:2015/01/25

3. Instance method

The instance methods of a Date object are divided into 2 main forms: local time and UTC time. In the same way, there are typically 2 time format operations (method names with UTC, or UTC time), which mainly describes the operation of local time.

3.1 Get method

• getFullYear (): Returns the year value of the Date object; 4-bit year.
• GetMonth (): Returns the month value of the Date object. Starting from 0, so the real month = Returns the value +1.
• GetDate (): Returns the date value in the month of the Date object, 1~31 the range of the value.
• GetHours (): Returns a Date object's small value.
• Getminutes (): Returns the minute value of a Date object.
• Getseconds (): Returns the number of seconds for a Date object.
• Getmilliseconds (): Returns the millisecond value of the Date object.
• Getday (): Returns the week value of the week for the date object, 0 for Sunday, 1 for Monday, 2 for Tuesday, and so on
• GetTime (): Returns the millisecond value between the Date object and ' 1970/01/01 00:00:00 ' (The time zone in Beijing is East 8, and the starting time is actually: ' 1970/01/01 08:00:00 ').

Example:

Dt.getfullyear (); => 2014: Year
dt.getmonth ();//=> 11: Month; actual for December (month starting from 0)
dt.getdate ();//=> 25: Day
dt.gethours (); /=> 15: Time
dt.getminutes ()//=> 30: Sub
dt.getseconds ();//=> 40: Sec
dt.getmilliseconds ();//=> 333 : Millisecond
dt.getday ();//=> 4: The value of the day of the Week
Dt.gettime ();//=> 1419492640333: Returns the millisecond value between the Date object and ' 1970/01/01 00:00:00 ' ( The time zone in Beijing is East 8, the starting time is actually: ' 1970/01/01 08:00:00 ')

3.2 Set method

• setFullYear (year, Opt_month, opt_date): Sets the Date object's age value, 4-bit year.
• Setmonth (Month, opt_date): Sets the month value of the Date object. 0 indicates January, 11 represents December.
• Setdate (date): Sets the date value in the month of the date object; 1~31 the range of the value.
• Sethours (Hour, opt_min, Opt_sec, opt_msec): Sets the Date object's small values.
• Setminutes (Min, Opt_sec, opt_msec): Sets the minute value of the Date object.
• Setseconds (sec, opt_msec): Sets the number of seconds for a Date object.
• Setmilliseconds (msec): Sets the millisecond value of the Date object.

Example:

var dt = new Date ();
Dt.setfullyear (2014); => 2014: Year
dt.setmonth (one);//=> 11: Month; actual for December (month starting from 0)
dt.setdate;//=> 25: Day
dt.sethours (15); => 15:
dt.setminutes//=> 30: Min
dt.setseconds (s);//=> 40: Sec
dt.setmilliseconds (333); => 333: Millisecond
console.log (DT);//=> December 25, 2014 15:30 40 second 333 ms

3.3 Other methods

• ToString (): Converts date to a ' date and time ' string
• toLocaleString (): Converts date to a local format string with a ' month and a day '
• toDateString (): Converts date to a ' month-day ' string
• toLocaleDateString (): Converts date to a local format string of ' year/month '
• toTimeString (): Converts date to a ' time and seconds ' string
• toLocaleTimeString (): Converts date to a local format string of ' time and seconds '

ValueOf (): As with gettime (), returns the millisecond value between the Date object and ' 1970/01/01 00:00:00 ' (The time zone in Beijing is East 8, and the starting time is actually: ' 1970/01/01 08:00:00 ')

Example:

var dt = new Date ();
Console.log (Dt.tostring ());  => Tue Dec 2014 22:56:11 gmt+0800 (China Standard Time): convert date to a ' date and time ' string
console.log (dt.tolocalestring ());//=> December 23, 2014 10:56:11: Converts date to a local format string Console.log (Dt.todatestring ()) with a ' month and a day '

;//=> Tue DEC 23 2014: Turn date Change to a ' year and a day ' string
console.log (dt.tolocaledatestring ());//=> December 23, 2014: convert date to a local format string

of ' year/month ' Console.log (Dt.totimestring ()); => 22:56:11 gmt+0800 (China Standard Time): convert date to a ' time and seconds ' string
console.log (dt.tolocaletimestring ());//=> 10:56:11 : Converts date to a local format string Console.log (Dt.valueof ()) with a ' time and minutes '

;//=> returns the millisecond value between the Date object and ' 1970/01/01 00:00:00 ' (The time zone in Beijing is East 8, The starting time is actually: ' 1970/01/01 08:00:00 ')

4. Static method

4.1 Date.now ()

Description: Returns the millisecond value between the Date object and the ' 1970/01/01 00:00:00 ' (The time zone in Beijing is East 8, and the starting time is actually: ' 1970/01/01 08:00:00 ')

Parameters: None

return value:

{int}: The number of milliseconds between the current time and the start time.

Example:

Console.log (Date.now ()); => 1419431519276

4.2 Date.parse (DATESTR)

Description: Converts a string to a Date object and returns the millisecond value between this Date object and ' 1970/01/01 00:00:00 ' (The time zone in Beijing is East 8, and the starting time is actually: ' 1970/01/01 08:00:00 ')

Parameters:

①datestr {string}: a string that can be converted to a Date object (can be omitted); There are two main types of strings:

1) yyyy/mm/dd HH:mm:ss (recommended): If you omit the time, the date object returned time is 00:00:00.

2) Yyyy-mm-dd HH:mm:ss: If the time is omitted, the Date object returned is 08:00:00 (plus the local time zone). If you do not omit the time, this string returns Nan (not a number) in IE!

return value:

{int} returns the number of milliseconds between the converted Date object and the start time.

Example:

Console.log (Date.parse (' 2014/12/25 12:00:00 ')); => 1419480000000
console.log (Date.parse (' 2014-12-25 12:00:00 '));//=> 1419480000000 (Note: This conversion mode is returned in IE nan! )

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Click here: "How JavaScript Gets the system's current time"

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The above is the entire content of this article, I hope that through this article we know more about JavaScript Date object, we common progress.