Learn JavaScript with me Date object _javascript tips

Source: Internet
Author: User
Tags getdate instance method local time time and seconds

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! )

Two stories to share:

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

Click to view: "JavaScript Dealer website snapped the countdown effect realization"

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.

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