javascript中的EventTarget

The W3C DOM EventTarget object is the events module connection with nodes that actually receive events. All node objects (especially text and element nodes in an HTML document tree) implement the EventTarget object, thus giving those nodes the three methods that belong to the EventTarget object:addEventListener( ), dispatchEvent( ) , and  removeEventListener( ) . In other words, every node in a document is also an EventTarget object.

W3C DOM中的EventTarget对象是接收事件的节点的事件模块连接。所有的节点对象（特别是HTML对象树中文本和元素节点）实现EventTarget对象。所以这些节点都有下面三个属于EventTarget的方法：addEventListener(),dispatchEvent(),和removeEventListener()。换就话说，document中的每一个节点也是一个EventTarget对象。