These docs are for an old release. Info on upgrading to v4
edit doc

dateIncrement 3.3.0

How far into the future/past the calendar navigates when prev/next is executed.

Duration-ish object

Determines how far the calendar will jump when the user presses the prev/next buttons in the header or when the prev or next methods are executed.

When using a standard view, it is unnecessary to specify dateIncrement.

When using a Custom View with a specified duration, the duration value will be the default for dateIncrement.