Gets or sets the placement to be used for this Menu relative to the target object.
This value is overridden by the value of placement passed in the show method.
var placement = menu.placement; menu.placement = placement;
The placement of the Menu relative to the target: the string literal "auto", "top", "bottom", "left", or "right". The default is "auto".
If the value is "auto", the menu is placed such that the entire menu can be shown without being resized.
If the value is "top", "bottom", "left", or "right", the menu is shown on the side specified and, if necessary, resized to fit.
Minimum WinJS version
Guidelines for flyouts
Guidelines for context menus