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Date

Lets you work with dates and times.

Core object

Implemented in

Navigator 2.0, LiveWire 1.0
Navigator 3.0: added prototype property

Created by

The Date constructor:

new Date()
new Date("month day, year hours:minutes:seconds")
new Date(yr_num, mo_num, day_num)
new Date(yr_num, mo_num, day_num, hr_num, min_num, sec_num)

Parameters

month, day, year,
hours, minutes,
seconds
String values representing part of a date.

yr_num, mo_num,
day_num, hr_num,
min_num, sec_num
Integer values representing part of a date. As an integer value, the month is represented by 0 to 11 with 0=January and 11=December.

Description

If you supply no arguments, the constructor creates a Date object for today's date and time. If you supply some arguments, but not others, the missing arguments are set to 0. If you supply any arguments, you must supply at least the year, month, and day. You can omit the hours, minutes, and seconds.

The way JavaScript handles dates is very similar to the way Java handles dates: both languages have many of the same date methods, and both store dates internally as the number of milliseconds since January 1, 1970 00:00:00. Dates prior to 1970 are not allowed.

Property Summary

prototype
Allows the addition of properties to a Date object.

Method Summary

getDate
Returns the day of the month for the specified date.

getDay
Returns the day of the week for the specified date.

getHours
Returns the hour in the specified date.

getMinutes
Returns the minutes in the specified date.

getMonth
Returns the month in the specified date.

getSeconds
Returns the seconds in the specified date.

getTime
Returns the numeric value corresponding to the time for the specified date.

getTimezoneOffset
Returns the time-zone offset in minutes for the current locale.

getYear
Returns the year in the specified date.

parse
Returns the number of milliseconds in a date string since January 1, 1970, 00:00:00, local time.

setDate
Sets the day of the month for a specified date.

setHours
Sets the hours for a specified date.

setMinutes
Sets the minutes for a specified date.

setMonth
Sets the month for a specified date.

setSeconds
Sets the seconds for a specified date.

setTime
Sets the value of a Date object.

setYear
Sets the year for a specified date.

toGMTString
Converts a date to a string, using the Internet GMT conventions.

toLocaleString
Converts a date to a string, using the current locale's conventions.

UTC
Returns the number of milliseconds in a Date object since January 1, 1970, 00:00:00, Universal Coordinated Time (GMT).

Examples

The following examples show several ways to assign dates:

today = new Date()
birthday = new Date("December 17, 1995 03:24:00")
birthday = new Date(95,11,17)
birthday = new Date(95,11,17,3,24,0)

Properties

prototype

Represents the prototype for this class. You can use the prototype to add properties or methods to all instances of a class. For information on prototypes, see Function.prototype.

Property of

Date

Implemented in

Navigator 3.0, LiveWire 1.0

Methods

getDate

Returns the day of the month for the specified date.

Method of

Date

Implemented in

Navigator 2.0, LiveWire 1.0

Syntax

getDate()

Parameters

None

Description

The value returned by getDate is an integer between 1 and 31.

Examples

The second statement below assigns the value 25 to the variable day, based on the value of the Date object Xmas95.

Xmas95 = new Date("December 25, 1995 23:15:00")
day = Xmas95.getDate()

See also

Date.setDate

getDay

Returns the day of the week for the specified date.

Method of

Date

Implemented in

Navigator 2.0, LiveWire 1.0

Syntax

getDay()

Parameters

None

Description

The value returned by getDay is an integer corresponding to the day of the week: 0 for Sunday, 1 for Monday, 2 for Tuesday, and so on.

Examples

The second statement below assigns the value 1 to weekday, based on the value of the Date object Xmas95. December 25, 1995, is a Monday.

Xmas95 = new Date("December 25, 1995 23:15:00")
weekday = Xmas95.getDay()

getHours

Returns the hour for the specified date.

Method of

Date

Implemented in

Navigator 2.0, LiveWire 1.0

Syntax

getHours()

Parameters

None

Description

The value returned by getHours is an integer between 0 and 23.

Examples

The second statement below assigns the value 23 to the variable hours, based on the value of the Date object Xmas95.

Xmas95 = new Date("December 25, 1995 23:15:00")
hours = Xmas95.getHours()

See also

Date.setHours

getMinutes

Returns the minutes in the specified date.

Method of

Date

Implemented in

Navigator 2.0, LiveWire 1.0

Syntax

getMinutes()

Parameters

None

Description

The value returned by getMinutes is an integer between 0 and 59.

Examples

The second statement below assigns the value 15 to the variable minutes, based on the value of the Date object Xmas95.

Xmas95 = new Date("December 25, 1995 23:15:00")
minutes = Xmas95.getMinutes()

See also

Date.setMinutes

getMonth

Returns the month in the specified date.

Method of

Date

Implemented in

Navigator 2.0, LiveWire 1.0

Syntax

getMonth()

Parameters

None

Description

The value returned by getMonth is an integer between 0 and 11. 0 corresponds to January, 1 to February, and so on.

Examples

The second statement below assigns the value 11 to the variable month, based on the value of the Date object Xmas95.

Xmas95 = new Date("December 25, 1995 23:15:00")
month = Xmas95.getMonth()

See also

Date.setMonth

getSeconds

Returns the seconds in the current time.

Method of

Date

Implemented in

Navigator 2.0, LiveWire 1.0

Syntax

getSeconds()

Parameters

None

Description

The value returned by getSeconds is an integer between 0 and 59.

Examples

The second statement below assigns the value 30 to the variable secs, based on the value of the Date object Xmas95.

Xmas95 = new Date("December 25, 1995 23:15:30")
secs = Xmas95.getSeconds()

See also

Date.setSeconds

getTime

Returns the numeric value corresponding to the time for the specified date.

Method of

Date

Implemented in

Navigator 2.0, LiveWire 1.0

Syntax

getTime()

Parameters

None

Description

The value returned by the getTime method is the number of milliseconds since 1 January 1970 00:00:00. You can use this method to help assign a date and time to another Date object.

Examples

The following example assigns the date value of theBigDay to sameAsBigDay:

theBigDay = new Date("July 1, 1999")
sameAsBigDay = new Date()
sameAsBigDay.setTime(theBigDay.getTime())

See also

Date.setTime

getTimezoneOffset

Returns the time-zone offset in minutes for the current locale.

Method of

Date

Implemented in

Navigator 2.0, LiveWire 1.0

Syntax

getTimezoneOffset()

Parameters

None

Description

The time-zone offset is the difference between local time and Greenwich Mean Time (GMT). Daylight savings time prevents this value from being a constant.

Examples

x = new Date()
currentTimeZoneOffsetInHours = x.getTimezoneOffset()/60

getYear

Returns the year in the specified date.

Method of

Date

Implemented in

Navigator 2.0, LiveWire 1.0

Syntax

getYear()

Parameters

None

Description

The getYear method returns either a 2-digit or 4-digit year:

Examples

Example 1. The second statement assigns the value 95 to the variable year.

Xmas = new Date("December 25, 1995 23:15:00")
year = Xmas.getYear()
Example 2. The second statement assigns the value 2000 to the variable year.

Xmas = new Date("December 25, 2000 23:15:00")
year = Xmas.getYear()
Example 3. The second statement assigns the value 95 to the variable year, representing the year 1995.

Xmas.setYear(95)
year = Xmas.getYear()

See also

Date.setYear

parse

Returns the number of milliseconds in a date string since January 1, 1970, 00:00:00, local time.

Method of

Date

Static

Implemented in

Navigator 2.0, LiveWire 1.0

Syntax

Date.parse(dateString)

Parameters

:

dateString
A string representing a date.

Description

The parse method takes a date string (such as "Dec 25, 1995") and returns the number of milliseconds since January 1, 1970, 00:00:00 (local time). This function is useful for setting date values based on string values, for example in conjunction with the setTime method and the Date object.

Given a string representing a time, parse returns the time value. It accepts the IETF standard date syntax: "Mon, 25 Dec 1995 13:30:00 GMT". It understands the continental US time-zone abbreviations, but for general use, use a time-zone offset, for example, "Mon, 25 Dec 1995 13:30:00 GMT+0430" (4 hours, 30 minutes west of the Greenwich meridian). If you do not specify a time zone, the local time zone is assumed. GMT and UTC are considered equivalent.

Because parse is a static method of Date, you always use it as Date.parse(), rather than as a method of a Date object you created.

Examples

If IPOdate is an existing Date object, then you can set it to August 9, 1995 as follows:

IPOdate.setTime(Date.parse("Aug 9, 1995"))

See also

Date.UTC

setDate

Sets the day of the month for a specified date.

Method of

Date

Implemented in

Navigator 2.0, LiveWire 1.0

Syntax

setDate(dayValue)

Parameters

dayValue
An integer from 1 to 31, representing the day of the month.

Examples

The second statement below changes the day for theBigDay to July 24 from its original value.

theBigDay = new Date("July 27, 1962 23:30:00")
theBigDay.setDate(24)

See also

Date.getDate

setHours

Sets the hours for a specified date.

Method of

Date

Implemented in

Navigator 2.0, LiveWire 1.0

Syntax

setHours(hoursValue)

Parameters

hoursValue
An integer between 0 and 23, representing the hour.

Examples

theBigDay.setHours(7)

See also

Date.getHours

setMinutes

Sets the minutes for a specified date.

Method of

Date

Implemented in

Navigator 2.0, LiveWire 1.0

Syntax

setMinutes(minutesValue)

Parameters

minutesValue
An integer between 0 and 59, representing the minutes.

Examples

theBigDay.setMinutes(45)

See also

Date.getMinutes

setMonth

Sets the month for a specified date.

Method of

Date

Implemented in

Navigator 2.0, LiveWire 1.0

Syntax

setMonth(monthValue)

Parameters

monthValue
An integer between 0 and 11 (representing the months January through December).

Examples

theBigDay.setMonth(6)

See also

Date.getMonth

setSeconds

Sets the seconds for a specified date.

Method of

Date

Implemented in

Navigator 2.0, LiveWire 1.0

Syntax

setSeconds(secondsValue)

Parameters

secondsValue
An integer between 0 and 59.

Examples

theBigDay.setSeconds(30)

See also

Date.getSeconds

setTime

Sets the value of a Date object.

Method of

Date

Implemented in

Navigator 2.0, LiveWire 1.0

Syntax

setTime(timevalue) 

Parameters

timevalue
An integer representing the number of milliseconds since 1 January 1970 00:00:00.

Description

Use the setTime method to help assign a date and time to another Date object.

Examples

theBigDay = new Date("July 1, 1999")
sameAsBigDay = new Date()
sameAsBigDay.setTime(theBigDay.getTime())

See also

Date.getTime

setYear

Sets the year for a specified date.

Method of

Date

Implemented in

Navigator 2.0, LiveWire 1.0

Syntax

setYear(yearValue)

Parameters

yearValue
An integer.

Description

If yearValue is a number between 0 and 99 (inclusive), then the year for dateObjectName is set to 1900 + yearValue. Otherwise, the year for dateObjectName is set to yearValue.

Examples

Note that there are two ways to set years in the 20th century.

Example 1. The year is set to 1996.

theBigDay.setYear(96)
Example 2. The year is set to 1996.

theBigDay.setYear(1996)
Example 3. The year is set to 2000.

theBigDay.setYear(2000)

See also

Date.getYear

toGMTString

Converts a date to a string, using the Internet GMT conventions.

Method of

Date

Implemented in

Navigator 2.0, LiveWire 1.0

Syntax

toGMTString()

Parameters

None

Description

The exact format of the value returned by toGMTString varies according to the platform.

Examples

In the following example, today is a Date object:

today.toGMTString()
In this example, the toGMTString method converts the date to GMT (UTC) using the operating system's time-zone offset and returns a string value that is similar to the following form. The exact format depends on the platform.

Mon, 18 Dec 1995 17:28:35 GMT

See also

Date.toLocaleString

toLocaleString

Converts a date to a string, using the current locale's conventions.

Method of

Date

Implemented in

Navigator 2.0, LiveWire 1.0

Syntax

toLocaleString()

Parameters

None

Description

If you pass a date using toLocaleString, be aware that different platforms assemble the string in different ways. Using methods such as getHours, getMinutes, and getSeconds gives more portable results.

Examples

In the following example, today is a Date object:

today = new Date(95,11,18,17,28,35) //months are represented by 0 to 11
today.toLocaleString()
In this example, toLocaleString returns a string value that is similar to the following form. The exact format depends on the platform.

12/18/95 17:28:35

See also

Date.toGMTString

UTC

Returns the number of milliseconds in a Date object since January 1, 1970, 00:00:00, Universal Coordinated Time (GMT).

Method of

Date

Static

Implemented in

Navigator 2.0, LiveWire 1.0

Syntax

Date.UTC(year, month, day, hrs, min, sec)

Parameters

year
A year after 1900.

month
A month between 0 and 11.

date
A day of the month between 1 and 31.

hrs
(Optional) A number of hours between 0 and 23.

min
(Optional) A number of minutes between 0 and 59.

sec
(Optional) A number of seconds between 0 and 59.

Description

UTC takes comma-delimited date parameters and returns the number of milliseconds since January 1, 1970, 00:00:00, Universal Coordinated Time (GMT).

Because UTC is a static method of Date, you always use it as Date.UTC(), rather than as a method of a Date object you created.

Examples

The following statement creates a Date object using GMT instead of local time:

gmtDate = new Date(Date.UTC(96, 11, 1, 0, 0, 0))

See also

Date.parse


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Last Updated: 10/31/97 16:00:33


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