javascript - setInterval 在选项卡/窗口不活动时变慢

Question

我构建了一个网络应用程序，并使用带有 500 毫秒计时器的 setInterval 作为一些时钟。

当窗口处于事件状态时，时钟运行完美，我使用它:

var tempTimer = 0;
setInterval(function () {
    goTimer()
}, 500);

function goTimer() {
    tempTimer++;
    $("#timer").val(tempTimer);
}

但问题是当窗口/选项卡变为非事件状态时 - 间隔更改为 1000 毫秒!

当我再次关注窗口/选项卡时，它变回 500 毫秒。

检查一下:http://jsfiddle.net/4Jw37/

非常感谢。

Answer 1

是的，这种行为是故意的。

参见 MDN article :

In (Firefox 5.0 / Thunderbird 5.0 / SeaMonkey 2.2) and Chrome 11, timeouts are clamped to firing no more often than once per second (1000ms) in inactive tabs; see bug 633421 for more information about this in Mozilla or crbug.com/66078 for details about this in Chrome.

还有 spec说:

Note: This API does not guarantee that timers will run exactly on schedule. Delays due to CPU load, other tasks, etc, are to be expected.