A custom React Hook to help you implement a dark mode component

use-dark-mode

A custom React Hook to help you implement a "dark mode" component for your application.

useDarkMode works in one of two ways:

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

Requirement ⚠️

To use use-dark-mode, you must use react@16.8.0-alpha.0. React Hooks is currently at
RFC stage.

Installation

$ npm i use-dark-mode

Usage

const darkMode = useDarkMode(initialState, optionalConfigObject);

Config

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

Key	Description
`className`	The class to apply. Default = `dark-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 `className` and `element` are ignored (i.e. no classes are automatically placed on the DOM). You have full control!

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.

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 Toggle from './Toggle';
import useDarkMode from 'use-dark-mode';

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;