@pablosz/use-dark-mode

use-dark-mode

A custom React Hook to help you implement a "dark mode" component for your application. The user setting persists to localStorage.

❤️ it? ⭐️ it on GitHub.

useDarkMode works in one of two ways:

1. By toggling a CSS class on whatever element you specify (defaults to document.body). You then setup your CSS to display different views based on the presence of the selector. For example, the following CSS is used in the demo app to ease the background color in/out of dark mode.

   body.light-mode {
     background-color: #fff;
     color: #333;
     transition: background-color 0.3s ease;
   }
   body.dark-mode {
     background-color: #1a1919;
     color: #999;
   }

2. If you don't use global classes, you can specify an onChange handler and take care of the implementation of switching to dark mode yourself.

New in Version 2.x

• useDarkMode now persists between sessions. It stores the user setting in localStorage.

• It shares dark mode state with all other useDarkMode components on the page.

• It shares dark mode state with all other tabs/browser windows.

• The initial dark mode is queried from the system. Note: this requires a browser that supports the prefers-color-scheme: dark media query (currently only Safari Technology Preview) and a system that supports dark mode, such as macOS Mojave.

• Changing the system dark mode state will also change the state of useDarkMode (i.e, change to light mode in the system will change to light mode in your app).

• Support for Server Side Rendering (SSR) in version 2.2 and above.

Requirement

To use use-dark-mode, you must use react@16.8.0 or greater which includes Hooks.

Installation

$ npm i use-dark-mode

Usage

const darkMode = useDarkMode(initialState, darkModeConfig);

Parameters

You pass useDarkMode an initialState (a boolean specifying whether it should be in dark mode by default) and an optional darkModeConfig object. The configuration object may contain the following keys.

Key	Description
classNameDark	The class to apply. Default = dark-mode.
classNameLight	The class to apply. Default = light-mode.
element	The element to apply the class name. Default = document.body.
onChange	A function that will be called when the dark mode value changes and it is safe to access the DOM (i.e. it is called from within a useEffect). If you specify onChange then classNameDark, classNameLight, and element are ignored (i.e. no classes are automatically placed on the DOM). You have full control!
storageKey	A string that will be used by the storageProvider to persist the dark mode value. If you specify a value of null, nothing will not be persisted. Default = darkMode.
storageProvider	A storage provider. Default = localStorage. You will generally never need to change this value.

Return object

A darkMode object is returned with the following properties.

Key	Description
value	A boolean containing the current state of dark mode.
enable()	A function that allows you to set dark mode to true.
disable()	A function that allows you to set dark mode to false.
toggle()	A function that allows you to toggle dark mode.

Note that because the methods don't require any parameters, you can call them direcly from an onClick handler from a button, for example (i.e., no lambda function is required).

Example

Here is a simple component that uses useDarkMode to provide a dark mode toggle control. If dark mode is selected, the CSS class dark-mode is applied to document.body and is removed when de-selected.

import React from 'react';
import useDarkMode from 'use-dark-mode';

import Toggle from './Toggle';

const DarkModeToggle = () => {
  const darkMode = useDarkMode(false);

  return (
    <div>
      <button type="button" onClick={darkMode.disable}>
        ☀
      </button>
      <Toggle checked={darkMode.value} onChange={darkMode.toggle} />
      <button type="button" onClick={darkMode.enable}>
        ☾
      </button>
    </div>
  );
};

export default DarkModeToggle;

That flash!

If your CSS is setup to default to light mode, but the user selects dark mode, the next time they visit your app, they will be in dark mode. However, the user will see a flash of light mode before the app is spun up and useDarkMode is called.

To prevent this, I've included some vanilla JavaScript that you can insert in your index.html just after the <body> tag. It is in a file named noflash.js.txt. You can either insert the contents of this file in a <script> tag or automate the step in your build process.

Note that if you change any of the default—such as storageKey or classNameDark for example—the noflash.js file will need to be modified with the same values.

Sample Apps

Here is a list of apps build with use-dark-mode. If you have an app you would like to include on this list, open a PR.

• Demo App on CodeSandbox - by @donavon

License

MIT Licensed

Contributors

Thanks goes to these wonderful people (emoji key):

Donavon West 🚇 ⚠️ 💡 🤔 🚧 👀 🔧 💻	Revel Carlberg West 🤔	Mateusz Burzyński 💻	Justin Hall 💻	Jeremy 📓 🐛

This project follows the all-contributors specification. Contributions of any kind welcome!