javascript - mousemove 事件是否每帧触发一次？

Question

在此fiddle demo , 按下并移动鼠标将根据鼠标的位置绘制点。 draw 方法是监听 mousemove 回调，但它绘制了离散点，表明 mousemove 事件没有连续触发。

此外，我收集了 event.timeStamp 并登录了控制台。我发现相邻事件之间的偏移量接近 16.7 毫秒。那么 mousemove 事件是否每帧触发一次？

Answer 1

mousemove 事件频率是特定于实现的，未由任何规范定义。

A user agent MUST dispatch this event when a pointing device is moved while it is over an element. The frequency rate of events while the pointing device is moved is implementation-, device-, and platform-specific, but multiple consecutive mousemove events SHOULD be fired for sustained pointer-device movement, rather than a single event for each instance of mouse movement. Implementations are encouraged to determine the optimal frequency rate to balance responsiveness with performance.

-- UI Events, W3C Working Draft, 04 August 2016

某些平台上的某些浏览器完全有可能将其限制为每帧一次。但是，不能保证任何可能执行此操作的浏览器都会继续执行此操作。

如果你想画一条连续的线，你需要在每两个点之间创建插值数据。