Remix Themes

An abstraction for themes in your Remix app.

Features

✅ Perfect dark mode in a few lines of code
✅ System setting with prefers-color-scheme
✅ No flash on load
✅ Disable flashing when changing themes
✅ Class or data attribute selector
✅ Sync theme across tabs and windows

Check out the Example to see it in action.

Install

$ npm install remix-themes
# or
$ yarn add remix-themes

Getting Started

Create your session storage and create a themeSessionResolver

// sessions.server.tsx

import {createThemeSessionResolver} from 'remix-themes'
import { createCookieSessionStorage } from "@remix-run/node"

const sessionStorage = createCookieSessionStorage({
  cookie: {
    name: '__remix-themes',
    // domain: 'remix.run',
    path: '/',
    httpOnly: true,
    sameSite: 'lax',
    secrets: ['s3cr3t'],
    // secure: true,
  },
})

export const themeSessionResolver = createThemeSessionResolver(sessionStorage)

Note: make sure you have domain and secure parameters set only for your production environment. Otherwise, Safari won't store the cookie if you set these parameters on localhost.

Setup Remix Themes

// root.tsx

import {ThemeProvider, useTheme, PreventFlashOnWrongTheme} from 'remix-themes'
import {themeSessionResolver} from './sessions.server'

// Return the theme from the session storage using the loader
export const loader: LoaderFunction = async ({request}) => {
  const {getTheme} = await themeSessionResolver(request)
  return {
    theme: getTheme(),
  }
}

// Wrap your app with ThemeProvider.
// `specifiedTheme` is the stored theme in the session storage.
// `themeAction` is the action name that's used to change the theme in the session storage.
export default function AppWithProviders() {
  const data = useLoaderData()
  return (
    <ThemeProvider specifiedTheme={data.theme} themeAction="/action/set-theme">
      <App />
    </ThemeProvider>
  )
}

// Use the theme in your app.
// If the theme is missing in session storage, PreventFlashOnWrongTheme will get
// the browser theme before hydration and will prevent a flash in browser.
// The client code runs conditionally, it won't be rendered if we have a theme in session storage.
function App() {
  const data = useLoaderData()
  const [theme] = useTheme()
  return (
    <html lang="en" data-theme={theme ?? ''}>
      <head>
        <meta charSet="utf-8" />
        <meta name="viewport" content="width=device-width,initial-scale=1" />
        <Meta />
        <PreventFlashOnWrongTheme ssrTheme={Boolean(data.theme)} />
        <Links />
      </head>
      <body>
        <Outlet />
        <ScrollRestoration />
        <Scripts />
        {process.env.NODE_ENV === 'development' && <LiveReload />}
      </body>
    </html>
  )
}

Add the action route

Create a file in /routes/action/set-theme.ts or /routes/action.set-theme.ts when using Route File Naming v2 with the content below. Ensure that you pass the filename to the ThemeProvider component.

Note: You can name the action route whatever you want. Just make sure you pass the correct action name to the ThemeProvider component. Make sure to use absolute path when using nested routing.

This route is used to store the preferred theme in the session storage when the user changes it.

import {createThemeAction} from 'remix-themes'
import {themeSessionResolver} from './sessions.server'

export const action = createThemeAction(themeSessionResolver)

API

Let's dig into the details.

ThemeProvider

specifiedTheme: The theme from the session storage.
themeAction: The action name used to change the theme in the session storage.
disableTransitionOnThemeChange: Disable CSS transitions on theme change to prevent the flashing effect.

useTheme

useTheme takes no parameters but returns:

theme: Active theme name
setTheme: Function to set the theme. If the theme is set to null, the system theme will be used and definedBy property in the metadata object will be set to SYSTEM.
metadata: An object which contains the following properties:
- definedBy: The theme source. It can be USER or SYSTEM. Useful to detect if the theme was set by the user or by the system.

createThemeSessionResolver

createThemeSessionResolver function takes a cookie session storage and returns

resolver: A function that takes a request and returns an object with the following properties:
- getTheme: A function that returns the theme from the session storage.
- setTheme: A function that takes a theme name and sets it in the session storage.
- commit: A function that commits the session storage (Stores all data in the session and returns the Set-Cookie header to use in the HTTP response.)

PreventFlashOnWrongTheme

On the server, "theme" might be null so PreventFlashOnWrongTheme ensures that this is correct before hydration. If the theme is null on the server, this component will set the browser theme on the html element in a data-theme attribute if exists, otherwise it will be set to a class attribute. If both data-theme and class are set, the data-theme will be used.

ssrTheme: boolean value that indicates if we have a theme in the session storage.

abereghici / remix-themes

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