Question

This is the setup in short. I have a big table. Everytime a cell get focus an asyncron call to the server is done (with PageMethods) and some data is returned and updates a infobox in the page. I have written code that makes it possible to navigate between cells with the arrow keyes. The problem occurs when I shift focus fast through several cells in order to get to the cell I want. Every get-focus is executed and since the communication with the server takes about half a second it get quite irritating and not very user friendly. Ideally I would like to execute only the last focus event. But how? I cant know which event is the last one, can I? Ideas, anybody?

Answer 1

保罗说得对。

要在网络上执行此操作，您需要将当前的聚焦事件与javascript时间函数 SetTimeout和ClearTimeout结合使用：

var timer; // timer variable in scope for other functions

var onFocus = function() {
  clearTimeout(timer);
  timer = setTimeout("makePageMethodCall()", 500);
}

var makePageMethodCall = function() {
  // make ajax call to your PageMethod function
}

调用setTimeout()会在调用请求服务器方法之前创建半秒的等待时间。如果在定时器到期之前发生另一个焦点事件，则clearTimeout()调用将在启动另一个定时器之前取消当前定时器。正如Paolo建议的那样，您可以尝试使用500毫秒的时间长度，以找到最适合您情况的值。

Answer 2

原则上，当焦点事件被触发时，您需要一个短时间计时器开始倒计时。如果在计时器到期之前发生另一个事件，则重新启动计时器；否则，对于最后一个单元格执行OnFocus逻辑。

关键是要使它足够简短以保持UI的响应性，但又足够长避免触发多次对服务器的调用。

遗憾的是,我不知道你如何为协会工作。 NET,但我已就类似情况在Winforms做了工作。

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