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date.setTime(milliseconds)

Arguments

milliseconds

An integer expressing the number of milliseconds between the new desired date and midnight, January 1, 1970 � positive if after January 1, 1970; negative if before.

Returns

The value of milliseconds.

Description

Internally, all dates are represented as the number of milliseconds between the time of the date and midnight, January 1, 1970. The setTime( ) method specifies a new date using the internal millisecond representation. Setting a date using milliseconds from 1970 is often handy when we're determining differences between multiple dates and times using getTime( ).

Example

Using setTime( ) in concert with getTime( ), we can adjust the time of an existing date by adding or subtracting milliseconds. For example, here we add one hour to a date:

now = new Date();
now.setTime(now.getTime() + 3600000);

And here we add one day:

now = new Date();
now.setTime(now.getTime() + 86400000);

To improve the readability of our code, we create variables representing the number of milliseconds in an hour and milliseconds in a day:

oneDay = 86400000;
oneHour = 3600000;
now = new Date();
// Subtract one day and three hours.
now.setTime(now.getTime() - oneDay - (3 * oneHour));

See Also

Date.getTime( ), Date.setMilliseconds( ), Date.UTC( ), getTimer( )

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