Snake, in your tab

The game runs in this tab's icon, up in your browser's tab strip. Steer with the arrow keys or WASD, or the pad below. The score is in the tab's title. Until you press a key, the snake plays itself.

Score: 0
Best: 0

A tab icon is 16 pixels square, or 32 on a sharp screen, so the board is 16 cells across, two pixels each. Phones often don't show tab icons at all; there, the mirror above is all you get.

A clock that slows down when you leave

The icon is a clock with a sweeping second hand, redrawn by a timer four times a second. Switch to another tab and watch this one's icon and title. Browsers save power by holding back timers in background tabs, so the hand stops sweeping and starts to jump. Come back and this page shows what it managed while you were gone.

Redraws, last second: 0
Away: Not yet

Hum plays a quiet tone. Chrome doesn't hold back a tab that has made a sound in the last 30 seconds, so try leaving with it on, then with it off.

Chrome's rules

In a visible tab, timers run on time.
In a hidden tab, they wake at most once a second.
Hidden for five minutes, silent for 30 seconds, with a chain of five or more timers: at most once a minute.
requestAnimationFrame doesn't run at all in a hidden tab.

Firefox and Safari have rules of their own. The chart shows what your browser actually did.

Paint your own

Draw on the big icon above, and your tab follows along. The picture is kept in this browser; Save downloads it as a 32 pixel PNG.

An icon that moves by itself

Every other program here redraws the icon from script, frame after frame. This one hands the browser a single SVG file with an animation inside, and stops. If the icon in your tab spins, your browser animates icons on its own: Firefox does. If it sits still, your browser draws the first frame and keeps it: Chromium does, and a request to change that was closed as not planned.

The big copy above is the same file shown as an image in the page, where every browser animates it.

Wide color and HDR, in the tab

Two test icons, written byte by byte by this page as PNG files that name their color space in a cICP chunk. Put one in the tab, then compare the tab with the copies here.

Left, the reddest red in sRGB. Right, the reddest red in Display P3. On a wide-gamut screen, in a browser that keeps the color, the right half is redder.

Left, white at 203 nits, the brightness of SDR white. Right, white at 1,000 nits. On an HDR screen, in a browser that keeps HDR, the right half glows brighter than the page's white. On an ordinary screen, tone mapping can still leave the right half a little lighter.

Screen gamut: Unknown
Dynamic range: Unknown

If the copies here show the difference and the tab doesn't, your browser flattens its tab icons. If neither does, your screen or browser can't show it, and this test can't tell you more.

A sign across your tabs

Open this page in a few more tabs, side by side, with the + above or the link below. Every tab showing Strip joins the sign and holds one letter, and the message scrolls from tab to tab along your tab strip.

Open another tab

Message

This is the only tab on the sign.

Tabs take their places in the order they joined, which is usually left to right. If yours are out of order, number them, then drag the tabs to match or move them here.