MouseEvent()

MouseEvent() コンストラクタは、新しい MouseEvent を作成します。

 event = new MouseEvent(typeArg, mouseEventInit);

typeArg

イベント名を表す DOMString です。

mouseEventInit 省略可

Is a MouseEventInit dictionary, having the following fields:

• "screenX", optional and defaulting to 0, of type long, 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 and defaulting to 0, of type long, 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 and defaulting to 0, of type long, 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 and defaulting to 0, of type long, 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 and defaulting to false, of type Boolean, that indicates if the ctrl key was simultaneously pressed.
• "shiftKey", optional and defaulting to false, of type Boolean, that indicates if the shift key was simultaneously pressed.
• "altKey", optional and defaulting to false, of type Boolean, that indicates if the alt key was simultaneously pressed.
• "metaKey", optional and defaulting to false, of type Boolean, that indicates if the meta key was simultaneously pressed.
• "button", optional and defaulting to 0, of type short, 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 and defaulting to 0, of type unsigned short, 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 and defaulting to null, of type EventTarget, that is the element just left (in case of  a mouseenter (en-US) or mouseover (en-US)) or is entering (in case of a mouseout (en-US) or mouseleave (en-US)).
• "region", optional and defaulting to null, of type DOMString, is the id of the hit region affected by the event. The absence of any hit region is affected, is represented by the null value.

実装によっては、スクリーンとクライアントのフィールドに数値以外のものを渡すと TypeError がスローされます。

MouseEventInit ディクショナリは、UIEventInit (en-US) や EventInit ディクショナリのフィールドも受け入れます。

Internet Explorer 9 以降の MouseEvent() コンストラクタ機能は、以下のコードでポリフィルすることができます。

(function (window) {
  try {
    new MouseEvent('test');
    return false; // ポリフィル不要
  } catch (e) {
		// ポリフィルの必要性 - 落下
  }

    // ポリフィル DOM4 MouseEvent
	var MouseEventPolyfill = function (eventType, params) {
		params = params || { bubbles: false, cancelable: false };
		var mouseEvent = document.createEvent('MouseEvent');
		mouseEvent.initMouseEvent(eventType,
			params.bubbles,
			params.cancelable,
			window,
			0,
			params.screenX || 0,
			params.screenY || 0,
			params.clientX || 0,
			params.clientY || 0,
			params.ctrlKey || false,
			params.altKey || false,
			params.shiftKey || false,
			params.metaKey || false,
			params.button || 0,
			params.relatedTarget || null
		);

		return mouseEvent;
	}

	MouseEventPolyfill.prototype = Event.prototype;

	window.MouseEvent = MouseEventPolyfill;
})(window);

• MouseEvent, は、それが構築するオブジェクトのインターフェイス