Test One

I have written a test specifically for this purpose:

Frame Rate Distribution: setInterval vs requestAnimationFrame

^{Note: This test is quite CPU intensive. requestAnimationFrame is not supported by IE 9- and Opera 12-.}

The test logs the actual time it takes for a setInterval and requestAnimationFrame to run in different browsers, and gives you the results in the form of a distribution. You can change the number of milliseconds for setInterval to see how it runs under different settings. setTimeout works similarly to a setInterval with respect to delays. requestAnimationFrame generally defaults to the 60fps depending on the browser. To see what happens when you switch to a different tab or have an inactive window, simply open the page, switch to a different tab and wait for a while. It will continue to log the actual time it takes for these functions in an inactive tab.

Test Two

Another way to test it is to log the timestamp repeatedly with setInterval and requestAnimationFrame and view it in a detached console. You can see how frequently it is updated (or if it is ever updated) when you make the tab or window inactive.

• Test for setInterval


• Test for requestAnimationFrame

Results

Chrome

Chrome limits the minimum interval of setInterval to around 1000ms when the tab is inactive. If the interval is higher than 1000ms, it will run at the specified interval. It does not matter if the window is out of focus, the interval is limited only when you switch to a different tab. requestAnimationFrame is paused when the tab is inactive.

// Provides control over the minimum timer interval for background tabs.

const double kBackgroundTabTimerInterval = 1.0;

^{https://codereview.chromium.org/6546021/patch/1001/2001}

Firefox

Similar to Chrome, Firefox limits the minimum interval of setInterval to around 1000ms when the tab (not the window) is inactive. However, requestAnimationFrame runs exponentially slower when the tab is inactive, with each frame taking 1s, 2s, 4s, 8s and so on.

// The default shortest interval/timeout we permit

#define DEFAULT_MIN_TIMEOUT_VALUE 4 // 4ms

#define DEFAULT_MIN_BACKGROUND_TIMEOUT_VALUE 1000 // 1000ms

^{https://hg.mozilla.org/releases/mozilla-release/file/0bf1cadfb004/dom/base/nsGlobalWindow.cpp#l296}

Internet Explorer

IE does not limit the delay in setInterval when the tab is inactive, but it pauses requestAnimationFrame in inactive tabs. It does not matter whether the window is out of focus or not.

Edge

Starting from Edge 14, setInterval is capped at 1000ms in inactive tabs. requestAnimationFrame is always paused in inactive tabs.

Safari

Just like Chrome, Safari caps setInterval at 1000ms when the tab is inactive. requestAnimationFrame is paused as well.

Opera

Since the adoption of the Webkit engine, Opera exhibits the same behavior as Chrome. setInterval is capped at 1000ms and requestAnimationFrame is paused when the tab is inactive.

Summary

Repeating intervals for inactive tabs:

           setInterval     requestAnimationFrame

Chrome

9-         not affected    not supported

10         not affected    paused

11+        >=1000ms        paused



Firefox

3-         not affected    not supported

4          not affected    1s

5+         >=1000ms        2ns (n = number of frames since inactivity)



IE

9-         not affected    not supported

10+        not affected    paused



Edge

13-        not affected    paused

14+        >=1000ms        paused



Safari

5-         not affected    not supported

6          not affected    paused

7+         >=1000ms        paused



Opera

12-        not affected    not supported

15+        >=1000ms        paused