feat: handle theme with localStorage #456
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,141 @@ | ||
| import { ScriptOnce } from '@tanstack/react-router' | ||
| import { clientOnly, createIsomorphicFn } from '@tanstack/react-start' | ||
| import * as React from 'react' | ||
| import { createContext, ReactNode, useEffect, useState } from 'react' | ||
| import { z } from 'zod' | ||
|
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||
| const themeModeSchema = z.enum(['light', 'dark', 'auto']) | ||
| const resolvedThemeSchema = z.enum(['light', 'dark']) | ||
| const themeKey = 'theme' | ||
|
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| type ThemeMode = z.infer<typeof themeModeSchema> | ||
| type ResolvedTheme = z.infer<typeof resolvedThemeSchema> | ||
|
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| const getStoredThemeMode = createIsomorphicFn() | ||
| .server((): ThemeMode => 'auto') | ||
| .client((): ThemeMode => { | ||
| try { | ||
| const storedTheme = localStorage.getItem(themeKey) | ||
| return themeModeSchema.parse(storedTheme) | ||
| } catch { | ||
| return 'auto' | ||
| } | ||
| }) | ||
|
|
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| const setStoredThemeMode = clientOnly((theme: ThemeMode) => { | ||
| try { | ||
| const parsedTheme = themeModeSchema.parse(theme) | ||
| localStorage.setItem(themeKey, parsedTheme) | ||
| } catch {} | ||
| }) | ||
|
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| const getSystemTheme = createIsomorphicFn() | ||
| .server((): ResolvedTheme => 'light') | ||
| .client((): ResolvedTheme => { | ||
| return window.matchMedia('(prefers-color-scheme: dark)').matches | ||
| ? 'dark' | ||
| : 'light' | ||
| }) | ||
|
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| const updateThemeClass = clientOnly((themeMode: ThemeMode) => { | ||
| const root = document.documentElement | ||
| root.classList.remove('light', 'dark', 'auto') | ||
| const newTheme = themeMode === 'auto' ? getSystemTheme() : themeMode | ||
| root.classList.add(newTheme) | ||
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| if (themeMode === 'auto') { | ||
| root.classList.add('auto') | ||
| } | ||
| }) | ||
|
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| const setupPreferredListener = clientOnly(() => { | ||
| const mediaQuery = window.matchMedia('(prefers-color-scheme: dark)') | ||
| const handler = () => updateThemeClass('auto') | ||
| mediaQuery.addEventListener('change', handler) | ||
| return () => mediaQuery.removeEventListener('change', handler) | ||
| }) | ||
|
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| const getNextTheme = clientOnly((current: ThemeMode): ThemeMode => { | ||
| const themes: ThemeMode[] = | ||
| getSystemTheme() === 'dark' | ||
| ? ['auto', 'light', 'dark'] | ||
| : ['auto', 'dark', 'light'] | ||
| return themes[(themes.indexOf(current) + 1) % themes.length] | ||
| }) | ||
|
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| const themeDetectorScript = (function () { | ||
| function themeFn() { | ||
| try { | ||
| const storedTheme = localStorage.getItem('theme') || 'auto' | ||
| const validTheme = ['light', 'dark', 'auto'].includes(storedTheme) | ||
| ? storedTheme | ||
| : 'auto' | ||
|
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| if (validTheme === 'auto') { | ||
| const autoTheme = window.matchMedia('(prefers-color-scheme: dark)') | ||
| .matches | ||
| ? 'dark' | ||
| : 'light' | ||
| document.documentElement.classList.add(autoTheme, 'auto') | ||
| } else { | ||
| document.documentElement.classList.add(validTheme) | ||
| } | ||
| } catch (e) { | ||
| const autoTheme = window.matchMedia('(prefers-color-scheme: dark)') | ||
|
Contributor
There was a problem hiding this comment. why do we call this again? when does the above throw?
Member
Author
There was a problem hiding this comment. This is just in case accessing localStorage fails |
||
| .matches | ||
| ? 'dark' | ||
| : 'light' | ||
| document.documentElement.classList.add(autoTheme, 'auto') | ||
| } | ||
| } | ||
| return `(${themeFn.toString()})();` | ||
| })() | ||
|
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| type ThemeContextProps = { | ||
| themeMode: ThemeMode | ||
| resolvedTheme: ResolvedTheme | ||
| setTheme: (theme: ThemeMode) => void | ||
| toggleMode: () => void | ||
| } | ||
| const ThemeContext = createContext<ThemeContextProps | undefined>(undefined) | ||
|
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| type ThemeProviderProps = { | ||
| children: ReactNode | ||
| } | ||
| export function ThemeProvider({ children }: ThemeProviderProps) { | ||
| const [themeMode, setThemeMode] = useState<ThemeMode>(getStoredThemeMode) | ||
|
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| useEffect(() => { | ||
|
Contributor
There was a problem hiding this comment. do we really need that effect? cant we just execute it whenever setTheme is called?
Member
Author
There was a problem hiding this comment. I can move |
||
| if (themeMode !== 'auto') return | ||
| return setupPreferredListener() | ||
| }, [themeMode]) | ||
|
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| const resolvedTheme = themeMode === 'auto' ? getSystemTheme() : themeMode | ||
|
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| const setTheme = (newTheme: ThemeMode) => { | ||
| setThemeMode(newTheme) | ||
| setStoredThemeMode(newTheme) | ||
| updateThemeClass(newTheme) | ||
| } | ||
|
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| const toggleMode = () => { | ||
| setTheme(getNextTheme(themeMode)) | ||
| } | ||
|
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| return ( | ||
| <ThemeContext.Provider | ||
| value={{ themeMode, resolvedTheme, setTheme, toggleMode }} | ||
| > | ||
| <ScriptOnce children={themeDetectorScript} /> | ||
| {children} | ||
| </ThemeContext.Provider> | ||
| ) | ||
| } | ||
|
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| export const useTheme = () => { | ||
| const context = React.useContext(ThemeContext) | ||
| if (!context) { | ||
| throw new Error('useTheme must be used within a ThemeProvider') | ||
| } | ||
| return context | ||
| } | ||
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do we have a subscription to theme change on the client? e.g. if i switch from dark to light mode on the client in my browser or OS settings, does this update the theme here as well?
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Yes, it's the
setupPreferredListenerfunction setting it up. While onautoif you change the theme for example on your OS setting it immediately updates on tanstack.com