stacker.news/components/dark-mode.js

76 lines
2.0 KiB
JavaScript

import { useEffect, useState } from 'react'
const handleThemeChange = (dark) => {
const root = window.document.documentElement
root.setAttribute('data-bs-theme', dark ? 'dark' : 'light')
}
const STORAGE_KEY = 'darkMode'
const PREFER_DARK_QUERY = '(prefers-color-scheme: dark)'
const getTheme = () => {
const mql = window.matchMedia(PREFER_DARK_QUERY)
const supportsColorSchemeQuery = mql.media === PREFER_DARK_QUERY
let localStorageTheme = null
try {
localStorageTheme = window.localStorage.getItem(STORAGE_KEY)
} catch (err) {}
const localStorageExists = localStorageTheme !== null
if (localStorageExists) {
localStorageTheme = JSON.parse(localStorageTheme)
}
if (localStorageExists) {
return { user: true, dark: localStorageTheme }
} else if (supportsColorSchemeQuery) {
return { user: false, dark: mql.matches }
}
}
const setTheme = (dark) => {
window.localStorage.setItem(STORAGE_KEY, JSON.stringify(dark))
handleThemeChange(dark)
}
const listenForThemeChange = (onChange) => {
const mql = window.matchMedia(PREFER_DARK_QUERY)
mql.onchange = mql => {
const { user, dark } = getTheme()
if (!user) {
handleThemeChange(dark)
onChange({ user, dark })
}
}
window.onstorage = e => {
if (e.key === STORAGE_KEY) {
const dark = JSON.parse(e.newValue)
setTheme(dark)
onChange({ user: true, dark })
}
}
const root = window.document.documentElement
const observer = new window.MutationObserver(() => {
const theme = root.getAttribute('data-bs-theme')
onChange(dark => ({ ...dark, dark: theme === 'dark' }))
})
observer.observe(root, { attributes: true, attributeFilter: ['data-bs-theme'] })
return () => observer.disconnect()
}
export default function useDarkMode () {
const [dark, setDark] = useState()
useEffect(() => {
const { user, dark } = getTheme()
setDark({ user, dark })
listenForThemeChange(setDark)
}, [])
return [dark?.dark, () => {
setTheme(!dark.dark)
setDark({ user: true, dark: !dark.dark })
}]
}