eventTarget.dispatchEvent(event)

• event <Event>

• 返回：<boolean> 如果任一事件的 cancelable 属性值为 false 或者未调用其 preventDefault() 方法，则为 true，否则为 false。

  ¥Returns: <boolean> true if either event's cancelable attribute value is false or its preventDefault() method was not invoked, otherwise false.

将 event 调度到 event.type 的句柄列表。

¥Dispatches the event to the list of handlers for event.type.

注册的事件监听器按照注册的顺序同步地调用。

¥The registered event listeners is synchronously invoked in the order they were registered.