html <meta http-equiv="Accept-CH" content="DPR, Viewport-Width, Width"> ... <picture> <!-- serve WebP to Chrome and Opera --> <source media="(min-width: 50em)" sizes="50vw" srcset="/image/thing-200.webp 200w, /image/thing-400.webp 400w, /image/thing-800.webp 800w, /image/thing-1200.webp 1200w, /image/thing-1600.webp 1600w, /image/thing-2000.webp 2000w" type="image/webp"> <source sizes="(min-width: 30em) 100vw" srcset="/image/thing-crop-200.webp 200w, /image/thing-crop-400.webp 400w, /image/thing-crop-800.webp 800w, /image/thing-crop-1200.webp 1200w, /image/thing-crop-1600.webp 1600w, /image/thing-crop-2000.webp 2000w" type="image/webp"> <!-- serve JPEGXR to Edge --> <source media="(min-width: 50em)" sizes="50vw" srcset="/image/thing-200.jpgxr 200w, /image/thing-400.jpgxr 400w, /image/thing-800.jpgxr 800w, /image/thing-1200.jpgxr 1200w, /image/thing-1600.jpgxr 1600w, /image/thing-2000.jpgxr 2000w" type="image/vnd.ms-photo"> <source sizes="(min-width: 30em) 100vw" srcset="/image/thing-crop-200.jpgxr 200w, /image/thing-crop-400.jpgxr 400w, /image/thing-crop-800.jpgxr 800w, /image/thing-crop-1200.jpgxr 1200w, /image/thing-crop-1600.jpgxr 1600w, /image/thing-crop-2000.jpgxr 2000w" type="image/vnd.ms-photo"> <!-- serve JPEG to others --> <source media="(min-width: 50em)" sizes="50vw" srcset="/image/thing-200.jpg 200w, /image/thing-400.jpg 400w, /image/thing-800.jpg 800w, /image/thing-1200.jpg 1200w, /image/thing-1600.jpg 1600w, /image/thing-2000.jpg 2000w"> <source sizes="(min-width: 30em) 100vw" srcset="/image/thing-crop-200.jpg 200w, /image/thing-crop-400.jpg 400w, /image/thing-crop-800.jpg 800w, /image/thing-crop-1200.jpg 1200w, /image/thing-crop-1600.jpg 1600w, /image/thing-crop-2000.jpg 2000w"> <!-- fallback for browsers that don't support picture --> <img src="/image/thing.jpg" width="50%"> </picture>

```js // Log the full user-agent data navigator .userAgentData.getHighEntropyValues( ["architecture", "model", "bitness", "platformVersion", "fullVersionList"]) .then(ua => { console.log(ua) });

// output { "architecture":"x86", "bitness":"64", "brands":[ { "brand":" Not A;Brand", "version":"99" }, { "brand":"Chromium", "version":"98" }, { "brand":"Google Chrome", "version":"98" } ], "fullVersionList":[ { "brand":" Not A;Brand", "version":"99.0.0.0" }, { "brand":"Chromium", "version":"98.0.4738.0" }, { "brand":"Google Chrome", "version":"98.0.4738.0" } ], "mobile":false, "model":"", "platformVersion":"12.0.1" } ```

• Note: Client hints can also be specified in HTML using the <meta> element with the http-equiv attribute.

html <meta http-equiv="Accept-CH" content="Width, Downlink, Sec-CH-UA" />

• Example: http HTTP/1.1 200 OK Content-Type: text/html Accept-CH: Sec-CH-Prefers-Reduced-Motion Vary: Sec-CH-Prefers-Reduced-Motion Critical-CH: Sec-CH-Prefers-Reduced-Motion

```idl dictionary NavigatorUABrandVersion { DOMString brand; DOMString version; };

dictionary UADataValues { DOMString architecture; DOMString bitness; sequence<NavigatorUABrandVersion> brands; DOMString formFactor; sequence<NavigatorUABrandVersion> fullVersionList; DOMString model; boolean mobile; DOMString platform; DOMString platformVersion; DOMString uaFullVersion; // deprecated in favor of fullVersionList boolean wow64; };

dictionary UALowEntropyJSON { sequence<NavigatorUABrandVersion> brands; boolean mobile; DOMString platform; };

[Exposed=(Window,Worker)] interface NavigatorUAData { readonly attribute FrozenArray<NavigatorUABrandVersion> brands; readonly attribute boolean mobile; readonly attribute DOMString platform; Promise<UADataValues> getHighEntropyValues (sequence<DOMString> hints ); UALowEntropyJSON toJSON (); };

interface mixin NavigatorUA { [SecureContext] readonly attribute NavigatorUAData userAgentData ; };

Navigator includes NavigatorUA; WorkerNavigator includes NavigatorUA; ```

abnf Accept-Ranges: <range-unit> Accept-Ranges: none

```http GET http://localhost:50714/api/Car HTTP/1.1 User-Agent: Fiddler Host: localhost:50714 Range: x-entity=2-5

HTTP/1.1 206 Partial Content Cache-Control: no-cache Pragma: no-cache Content-Type: application/json; charset=utf-8 Content-Range: x-entity 2-5/10 Expires: -1 Server: Microsoft-IIS/8.0 Date: Tue, 31 Jul 2012 19:00:19 GMT Content-Length: 447

[{"Id":3,"Make":"Toyota","Model":"Yaris","BuildYear":2003,"Price":3750.0,... ```

```http GET /users

200 OK Accept-Ranges: users Content-Range: users 0-9/200

[ 0, …, 9 ] ```

```http GET /users Range: users=0-9

206 Partial Content Accept-Ranges: users Content-Range: users 0-9/200

[ 0, …, 9 ] ```

```http GET /users Range: users=0-9,50-59

206 Partial Content Accept-Ranges: users Content-Type: multipart/mixed; boundary=next

--next Content-Range: users 0-9/200

[ 0, …, 9 ]

--next Content-Range: users 50-59/200

[ 50, …, 59 ]

--next-- ```

```http GET /users?name=Fred

206 Partial Content Accept-Ranges: users Content-Range: users 0-100/*

[ 0, …, 100 ] ```

Add more languages to be sent in the HTTP Accept-Language header field: http Accept-Language: en-US,en;q=0.9,fr;q=0.8`

Larson, H., & Tajudeen, R. (n.d.). Vaccinating Africa against COVID-19: Riding a roller coaster of poor information. The Conversation. Retrieved 14 May 2021, from http://theconversation.com/vaccinating-africa-against-covid-19-riding-a-roller-coaster-of-poor-information-159716

(lazy checking)