Optionaltop?: numberThe top coordinate of the document window, if null then unchanged.
It should be specified relative to the top left corner if page specified relative using DestinationPropertiesBase#page or relative to the bottom left corner if page specified using DestinationPropertiesBase#pageIndex. See Destination description for details.
Display the page designated by DestinationPropertiesBase#page, with the vertical coordinate top positioned at the top edge of the window and the contents of the page magnified just enough to fit the entire width of the page within the window. A null value for top specifies that the current value of that parameter is to be retained unchanged.