The MouseEvent() constructor creates a new MouseEvent object.

type

A string with the name of the event. It is case-sensitive and browsers set it to dblclick, mousedown, mouseenter, mouseleave, mousemove, mouseout, mouseover, or mouseup.

options Optional

An object that, in addition of the properties defined in UIEvent(), can have the following properties:

screenX Optional

A number, defaulting to 0, that is the horizontal position of the mouse event on the user's screen; setting this value doesn't move the mouse pointer.

screenY Optional

A number, defaulting to 0, that is the vertical position of the mouse event on the user's screen; setting this value doesn't move the mouse pointer.

clientX Optional

A number, defaulting to 0, that is the horizontal position of the mouse event on the client window of user's screen; setting this value doesn't move the mouse pointer.

clientY Optional

A number, defaulting to 0, that is the vertical position of the mouse event on the client window of the user's screen; setting this value doesn't move the mouse pointer.

ctrlKey Optional

A boolean value indicating if the ctrl key was simultaneously pressed. It defaults to false.

shiftKey Optional

A boolean value indicating if the shift key was simultaneously pressed. It defaults to false.

altKey Optional

A boolean value indicating if the alt key was simultaneously pressed. It defaults to false.

metaKey Optional

A boolean value indicating if the meta key was simultaneously pressed. It defaults to false.

button Optional

A number, defaulting to 0, that describes which button is pressed during events related to the press or release of a button:

Value	Meaning
0	Main button pressed (usually the left button) or un-initialized
1	Auxiliary button pressed (usually the middle button)
2	Secondary button pressed (usually the right button)

buttons Optional

A number, defaulting to 0, that describes which buttons are pressed when the event is launched:

Bit-field value	Meaning
0	No button pressed
1	Main button pressed (usually the left button)
2	Secondary button pressed (usually the right button)
4	Auxiliary button pressed (usually the middle button)

relatedTarget Optional

An EventTarget, defaulting to null that is the element just left (in case of a mouseenter or mouseover) or is entering (in case of a mouseout or mouseleave).

region Non-standard Optional

A string, defaulting to null, that is the ID of the hit region affected by the event. The absence of any affected hit region is represented with the null value.

In some implementations, passing anything other than a number for the screen and client fields will throw a TypeError.

• MouseEvent, the interface of the objects it constructs.