有一个页面，我想定期做背景Ajax请求。因此，页面加载，那么它应该发在一定的时间Ajax请求。

There is a page and I want periodically to make "background" ajax requests. So the page is loaded then it should send ajax requests in a certain amount of time.

我会用cron了点。我从来没有使用previously所以我不知道是否会适合这项任务。有没有其他更简单的方法？

I might use cron for that. I have never use previously so I'm wondering if it would fit for that task. Is there any other more simple way?

P.S。的时间延迟将是约5分钟。

P.S. The time delay will be about 5 minutes.

推荐答案

由于在本质上是时间之间未知的延迟，你送出去，你收到一个完整的响应AJAX请求的时间，一个常常更好的方法是开始下一个AJAX调用时间固定金额的在的事先之一结束。这样一来，你也可以确保您的通话不重叠。

Since there is essentially an unknown delay between the time you send out an AJAX request and the time you receive a complete response for it, an oftentimes more elegant approach is to start the next AJAX call a fixed amount of time after the prior one finishes. This way, you can also ensure that your calls don't overlap.

var set_delay = 5000,
    callout = function () {
        $.ajax({
            /* blah */
        })
        .done(function (response) {
            // update the page
        })
        .always(function () {
            setTimeout(callout, set_delay);
        });
    };

// initial call
callout();