client-hints

client-hints

🕵️‍♂️ Parse client hints headers and provide a convenient API to access device information and user preferences

Use client hints, where available

import { ClientHints } from "client-hints";
import { userAgentParser } from "some-user-agent-parser-library";

app.get("/api-endpoint", (req, res) => {
  const hints = new ClientHints(req);

  const isMobile =
    hints.mobile ?? // cheap
    userAgentParser(req.get("user-agent")).device?.type === "mobile"; // more expensive

  const browserName =
    hints.vendorName ?? // cheap
    userAgentParser(req.get("user-agent")).browser?.name; // more expensive

  console.log(JSON.stringify(hints, null, 2)); // Serialises all available hints

  res.send(`${isMobile ? "Mobile" : "Desktop"} browser: ${browserName}`);
});

Available detections

All detections return undefined if the relevant header is not available.

Feature	Type	Header	Meaning	Adoption level
arch, architecture	string	Sec-CH-UA-Arch	CPU architecture	Experimental
bitness	number	Sec-CH-UA-Bitness	CPU bitness (32, 64)	Experimental
contentDpr, contentDevicePixelRatio	number	Content-DPR	Image device pixel ratio	Deprecated
deviceMemory	number	Device-Memory	Appr. available RAM	Experimental
downlink	number	Downlink	Network speed (Mbps)	Experimental
dpr, devicePixelRatio	number	DPR	Device pixel ratio	Deprecated
ect, effectiveConnectionType	string	ECT	Network profile (G)	Experimental
fetchDest, fetchDestination	string	Sec-Fetch-Dest	Resource type
fetchMode	string	Sec-Fetch-Mode	Navigation type
fetchSite	string	Sec-Fetch-Site	Relationship to origin
fetchUser	boolean	Sec-Fetch-User	Was the request triggered by user action
gpc	boolean	Sec-GPC	Consents to sell or share personal information	Experimental
mobile	boolean	Sec-CH-UA-Mobile	Boolean: Is this a mobile device	Experimental
model	string	Sec-CH-UA-Model	Device model	Experimental
platform	string	Sec-CH-UA-Platform	Operating system name	Experimental
platformVersion	string	Sec-CH-UA-Platform-Version	Operating system version	Experimental
prefersColorScheme	string	Sec-CH-Prefers-Color-Scheme	User's preferred color scheme	Experimental
prefersReducedMotion	boolean	Sec-CH-Prefers-Reduced-Motion	User prefers reduced motion	Experimental
prefersReducedTransparency	boolean	Sec-CH-Prefers-Reduced-Transparency	User prefers reduced transparency	Experimental
purpose	string	Sec-Purpose	Resource purpose (prefetch)	Experimental
vendorName	string	Sec-CH-UA / Sec-CH-UA-Full-Version-List	Browser Name	Experimental
vendorVersion	string	Sec-CH-UA-Full-Version / Sec-CH-UA / Sec-CH-UA-Full-Version-List	Browser version	Experimental
viewportWidth	number	Viewport-Width	Layout viewport width	Deprecated
width	number	Width	Resource desired width	Deprecated

Client Hints Instructions Response Header

Set the value of Accept-CH header to include the headers you want the browse to send.

Accept-CH: Sec-CH-UA-Mobile,Sec-CH-UA-Full-Version,Sec-CH-UA-Full-Version-List,Sec-CH-UA-Model,Sec-CH-UA-Platform,Sec-CH-UA-Platform-Version,ECT

Include all available hints:

Accept-CH: *