| export type ClientHint<Value> = { |
| cookieName: string |
| getValueCode: string |
| fallback: Value |
| transform?: (value: string) => Value |
| } |
|
|
| export type ClientHintsValue<ClientHintsRecord> = { |
| [K in keyof ClientHintsRecord]: ClientHintsRecord[K] extends ClientHint< |
| infer Value |
| > |
| ? ClientHintsRecord[K]['transform'] extends (value: string) => Value |
| ? ReturnType<ClientHintsRecord[K]['transform']> |
| : ClientHintsRecord[K]['fallback'] |
| : never |
| } |
|
|
| export function getHintUtils<Hints extends Record<string, ClientHint<any>>>( |
| hints: Hints |
| ) { |
| function getCookieValue(cookieString: string, name: string) { |
| const hint = hints[name] |
| if (!hint) { |
| throw new Error( |
| `Unknown client hint: ${typeof name === 'string' ? name : 'Unknown'}` |
| ) |
| } |
| const value = cookieString |
| .split(';') |
| .map((c: string) => c.trim()) |
| .find((c: string) => c.startsWith(hint.cookieName + '=')) |
| ?.split('=')[1] |
|
|
| return value ? decodeURIComponent(value) : null |
| } |
|
|
| function getHints(request?: Request): ClientHintsValue<Hints> { |
| const cookieString = |
| typeof document !== 'undefined' |
| ? document.cookie |
| : typeof request !== 'undefined' |
| ? (request.headers.get('Cookie') ?? '') |
| : '' |
|
|
| return Object.entries(hints).reduce((acc, [name, hint]) => { |
| const hintName = name |
| if ('transform' in hint) { |
| |
| acc[hintName] = hint.transform( |
| getCookieValue(cookieString, hintName) ?? hint.fallback |
| ) |
| } else { |
| |
| acc[hintName] = getCookieValue(cookieString, hintName) ?? hint.fallback |
| } |
| return acc |
| }, {} as ClientHintsValue<Hints>) |
| } |
|
|
| |
| |
| |
| |
| function getClientHintCheckScript() { |
| return ` |
| // This block of code allows us to check if the client hints have changed and |
| // force a reload of the page with updated hints if they have so you don't get |
| // a flash of incorrect content. |
| function checkClientHints() { |
| if (!navigator.cookieEnabled) return; |
| |
| // set a short-lived cookie to make sure we can set cookies |
| document.cookie = "canSetCookies=1; Max-Age=60; SameSite=Lax"; |
| const canSetCookies = document.cookie.includes("canSetCookies=1"); |
| document.cookie = "canSetCookies=; Max-Age=-1; path=/"; |
| if (!canSetCookies) return; |
| |
| const cookies = document.cookie.split(';').map(c => c.trim()).reduce((acc, cur) => { |
| const [key, value] = cur.split('='); |
| acc[key] = value; |
| return acc; |
| }, {}); |
| |
| let cookieChanged = false; |
| const hints = [ |
| ${Object.values(hints) |
| .map(hint => { |
| const cookieName = JSON.stringify(hint.cookieName) |
| return `{ name: ${cookieName}, actual: String(${hint.getValueCode}), value: cookies[${cookieName}] != null ? cookies[${cookieName}] : encodeURIComponent("${hint.fallback}") }` |
| }) |
| .join(',\n')} |
| ]; |
| for (const hint of hints) { |
| document.cookie = encodeURIComponent(hint.name) + '=' + encodeURIComponent(hint.actual) + '; Max-Age=31536000; path=/'; |
| if (decodeURIComponent(hint.value) !== hint.actual) { |
| cookieChanged = true; |
| } |
| } |
| if (cookieChanged) window.location.reload(); |
| } |
| |
| checkClientHints(); |
| ` |
| } |
|
|
| return { getHints, getClientHintCheckScript } |
| } |
|
|
| export const themeClientHint = { |
| cookieName: 'CH-prefers-color-scheme', |
| getValueCode: `window.matchMedia('(prefers-color-scheme: dark)').matches ? 'dark' : 'light'`, |
| fallback: 'light', |
| transform(value) { |
| return value === 'dark' ? 'dark' : 'light' |
| }, |
| } as const satisfies ClientHint<'dark' | 'light'> |
|
|
| |
| |
| |
| |
| |
| export function subscribeToSchemeChange( |
| subscriber: (value: 'dark' | 'light') => void, |
| cookieName: string = themeClientHint.cookieName |
| ) { |
| const schemaMatch = window.matchMedia('(prefers-color-scheme: dark)') |
| function handleThemeChange() { |
| const value = schemaMatch.matches ? 'dark' : 'light' |
| document.cookie = `${cookieName}=${value}; Max-Age=31536000; Path=/` |
| subscriber(value) |
| } |
| schemaMatch.addEventListener('change', handleThemeChange) |
| return function cleanupSchemaChange() { |
| schemaMatch.removeEventListener('change', handleThemeChange) |
| } |
| } |
|
|
