Date() constructor

Creates a JavaScript Date instance that represents a single moment in time in a platform-independent format. Date objects contain a Number that represents milliseconds since 1 January 1970 UTC.

尝试一下

Syntax

new Date()
new Date(value)
new Date(dateString)
new Date(year, monthIndex [, day [, hours [, minutes [, seconds [, milliseconds]]]]])

备注： The only correct way to instantiate a new Date object is by using the new operator. If you simply call the Date object directly, such as now = Date(), the returned value is a string rather than a Date object.

Parameters

There are four basic forms for the Date() constructor:

  1. No parameters

    When no parameters are provided, the newly-created Date object represents the current date and time as of the time of instantiation.

  2. Time value or timestamp number

    value

    An integer value representing the number of milliseconds since January 1, 1970, 00:00:00 UTC (the ECMAScript epoch, equivalent to the UNIX epoch), with leap seconds ignored. Keep in mind that most UNIX Timestamp functions are only accurate to the nearest second.

  3. Timestamp string

    dateString

    A string value representing a date, specified in a format recognized by the Date.parse() method. (These formats are IETF-compliant RFC 2822 timestamps, and also strings in a version of ISO8601.)

    备注： Parsing of date strings with the Date constructor (and Date.parse(), which works the same way) is strongly discouraged due to browser differences and inconsistencies.

    • Support for RFC 2822 format strings is by convention only.
    • Support for ISO 8601 formats differs in that date-only strings (e.g. "1970-01-01") are treated as UTC, not local.

  4. Individual date and time component values

    Given at least a year and month, this form of Date() returns a Date object whose component values (year, month, day, hour, minute, second, and millisecond) all come from the following parameters. Any missing fields are given the lowest possible value (1 for day and 0 for every other component).
    year

    Integer value representing the year.

    Values from 0 to 99 map to the years 1900 to 1999. All other values are the actual year. See the example below.

    monthIndex

    Integer value representing the month, beginning with 0 for January to 11 for December.

    day 可选

    Integer value representing the day of the month. The default is 1.

    hours 可选

    Integer value representing the hour of the day. The default is 0 (midnight).

    minutes 可选

    Integer value representing the minute segment of a time. The default is 0 minutes past the hour.

    seconds 可选

    Integer value representing the second segment of a time. The default is 0 seconds past the minute.

    milliseconds 可选

    Integer value representing the millisecond segment of a time. The default is 0 milliseconds past the second.

Specifications

Specification
ECMAScript Language Specification
# sec-date-constructor

Browser compatibility

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