JavaScript Date Object Introduction

Original: JavaScript Date Object Introduction

Date and Time object 1. Introduced

A Date object that is the object that operates on the date and time. The Date object operates on dates and times only through methods.

2. Constructor 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, indicating the number of milliseconds to begin stacking from ' 1970/01/01 00:00:00 '.

Note: The starting point of time to add the time zone of the current, Beijing times the timezone is the East 8 district, the starting time is actually: ' 1970/01/01 08:00:00 '

return value:

{Date} returns an overlay of the Date object.

Example:

var dt = new Date (1000 * 60 * 1); The number of milliseconds to forward 1 minutes console.log (DT); = = {Date}:1970/01/01 08:01:00DT = new Date (-1000 * 60 * 1); The number of milliseconds to reverse 1 minutes 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 (time can be omitted), and there are two main formats for strings:

1) yyyy/mm/dd HH:mm:ss (recommended): If time is omitted, the time of the returned Date object is 00:00:00.

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

return value:

{Date} returns a converted Date object.

Example:

2.4 New date (year, month, Opt_day, Opt_hours, Opt_minutes, Opt_seconds, opt_milliseconds): Converts the month-date, time-division-second 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 means December.

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

④opt_hours {int} optional: time, 2 digits, value 0~23.

⑤opt_minutes {int} optional: minute, 2 digits, value 0~59.

⑥opt_seconds {int} optional: seconds; 2 no number; value 0~59.

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

return value:

{Date} returns a converted Date object.

Example:

var dt = new Date (2014, 11); December 2014 (The month number entered here is one) console.log (DT); = = {Date}:2014/12/01 00:00:00DT = new Date (2014, 11, 25); December 25, 2014 Console.log (DT); = = {Date}:2014/12/25 00:00:00DT = new Date (2014, 11, 25, 15, 30, 40); December 25, 2014 15:30 40 sec console.log (DT); = = {Date}:2014/12/25 15:30:40DT = new Date (2014, 12, 25); March 25, 2014 (the month number entered here is 12, indicating the 13th month, jump to the second year of January) console.log (DT); + = {DATE}:2015/01/25

3. Properties

None; Date objects operate on dates and times only through methods.

4. Example Methods

The instance method of a Date object is divided into 2 main forms: local time and UTC time. The same method typically has this 2 time format operation (the method name is UTC, which is the operation of UTC time), which mainly describes the operation of local time.

4.1 Get Method 4.1.1 getFullYear (): Returns the year value of the Date object; 4-bit year. 4.1.2 GetMonth (): Returns the month value of the Date object. Starting from 0, so the real month = return value +1. 4.1.3 GetDate (): Returns the date value in the month of the date object; The range of values 1~31. 4.1.4 getHours (): Returns the hour value of the Date object. 4.1.5 getminutes (): Returns the minute value of the Date object. 4.1.6 getseconds (): Returns the second value of the Date object. 4.1.7 getmilliseconds (): Returns the millisecond value of the Date object. 4.1.8 GetDay (): Returns the day of the week of the date object, 0 for Sunday, 1 for Monday, 2 for Tuesday, and so on 4.1.9 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:

4.2 Set Method 4.2.1 setFullYear (year, Opt_month, opt_date): Sets the years value of the Date object; 4-bit year. 4.2.2 Setmonth (Month, opt_date): Sets the month value of the Date object. 0 represents January, 11 represents December. 4.2.3 SetDate (date): Sets the date value in the month of the date object; The range of values 1~31. 4.2.4 sethours (Hour, opt_min, Opt_sec, opt_msec): Sets the value of the Date object. 4.2.5 setminutes (min, Opt_sec, opt_msec): Sets the minute value of the Date object. 4.2.6 setseconds (sec, opt_msec): Sets the number of seconds for the date object. 4.2.7 setmilliseconds (msec): Sets the millisecond value of the Date object. Example:

var dt = new Date ();d t.setfullyear (2014); = 2014: Year dt.setmonth (11); = 11: Month; actual December (month starting from 0) dt.setdate (25); + 25: Day dt.sethours (15); = 15: Time Dt.setminutes (30); = 30: Sub-dt.setseconds (40); = 40: Seconds dt.setmilliseconds (333); = 333: Ms Console.log (DT); =  December 25, 2014 15:30 40 sec 333 ms

4.3 Other methods 4.3.1 toString (): Converts date to a ' month Day time Minute ' string 4.3.2 tolocalestring (): Converts a date to a ' month day time seconds ' local format string 4.3.3  toDateString (): Converts date to a ' month day ' string 4.3.4 tolocaledatestring (): a local format string that converts date to a ' month and day ' 4.3.5  toTimeString (): Converts date to a ' time seconds/minute ' string 4.3.6 tolocaletimestring (): Converts date to a ' time seconds ' local format string 4.3.7 valueof () : Same as 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 start time is actually: ' 1970/01/01 08:00:00 ')   Example:

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

5. Static method 5.1 Date.now ()

Description: returns the millisecond value between the Date object and ' 1970/01/01 00:00:00 ' in the current day and time (the time zone in Beijing time is East 8, and the starting point 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:

5.2 Date.parse (DATESTR)

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

Parameters:

①datestr {string}: A string that can be converted to a Date object (time can be omitted), and there are two main formats for strings:

1) yyyy/mm/dd HH:mm:ss (recommended): If time is omitted, the time of the returned Date object is 00:00:00.

2) Yyyy-mm-dd HH:mm:ss: If time is omitted, the time of the returned Date object 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 is returned in IE nan! )

6. Actual operation 6.1 The DateTime type of C # to a Date object of JS

Description: The datetime type of C # is returned to the foreground through JSON serialization in the format: "\/date (1419492640000) \". The median number that represents the number of milliseconds between the datetime value and the start time.

Example:

Backstage code: Simple ASHX

public void ProcessRequest (HttpContext context) {    System.Web.Script.Serialization.JavaScriptSerializer js = new System.Web.Script.Serialization.JavaScriptSerializer ();    DateTime dt = DateTime.Parse ("2014-12-25 15:30:40");    String rs = js. Serialize (DT); Serialized into JSON    context. Response.ContentType = "Text/plain";    Context. Response.Write (RS);}

Front Code:

6.2 Getting the Countdown

Description: calculates how many days the current time differs from the destination time.

Example:

/*** return countdown * @param dt {Date}: Destination Date Object * @return {Strin}: Return countdown: X days x x */function getdowntime (DT) {    //1. Get Countdown    var i Ntervalmsec = Dt-date.now (); Destination time minus the current time, get the difference between the two milliseconds    var intervalsec = intervalmsec/1000;//convert to seconds    var day = parseint (intervalsec/3600/ 24); Days    var hour = parseint ((intervalsec-day * 24 * 3600)/3600);//h    var min = parseint ((Intervalsec-day * 2 4 * 3600-hour * 3600)/60); Minutes    //2. If the difference between milliseconds is less than 0, indicating that the destination time is less than the current time, then the value is negative:-X day-time-minute, display, only show the number of days before negative on the line.    if (Intervalmsec < 0) {        hour = 0-hour;        min = 0-min;    }    3. Splice the string and return    var rs = day + ' days ' + hour + ' when ' + min + ' points ';    return RS;} Current time: 2014/12/28 13:26console.log (Getdowntime (New Date (' 2015/06/01 ')); = 154 days 10:33 console.log (getdowntime (' 2014/01/01 ')); +-361 days 13:26

6.3 Comparing the size of 2 date objects

Note: You can compare the number of milliseconds between 2 and the start time to differentiate the size.

Example:

var dt1 = new Date (' 2015/12/01 '), var dt2 = new Date (' 2015/12/25 '); Console.log (Dt1 > DT2); = False

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JavaScript Date Object Introduction