eventTarget.dispatchEvent(event)

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

将 event 调度到 event.type 的句柄列表。

注册的事件监听器按照注册的顺序同步地调用。

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

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

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