Initiates when the form filler moves the pointer into the area of the field, without necessarily pressing the mouse button. This event is not initiated when the pointer moves into the field for a different reason; for example, because an overlapping window closes.
You can use this event to provide visual feedback to a form filler in conjunction with the mouseExit event. For example, you can use this event to change the border or background color of an object to help visually indicate to form fillers that they are working in a specific field.
See also 

mouseEnter event