| | --- |
| | title: Dark Mode Toggle |
| | description: Dark mode without the flash of default theme |
| | date: 2021-04-21 |
| | draft: false |
| | slug: /pensieve/dark-mode-toggle |
| | tags: |
| | - Theming |
| | - Dark Mode |
| | --- |
| | |
| | Dark mode toggle without the flash of default theme. Important bits: |
| |
|
| | - CSS variables for color theming |
| | - Put `data-theme` attribute on `<html>`, not `<body>`, so we can run the JS before the DOM finishes rendering |
| | - Run local storage check in the `<head>` |
| | - JS for toggle button click handler can come after render |
| |
|
| | ## HTML |
| |
|
| | ```html |
| | <!DOCTYPE html> |
| | <html lang="en" data-theme="light"> |
| | <head> |
| | <meta charset="utf-8" /> |
| | <meta name="viewport" content="width=device-width, initial-scale=1.0" /> |
| | ... |
| | <script> |
| | // If there's a theme stored in localStorage, use it on the <html> |
| | const localStorageTheme = localStorage.getItem('theme'); |
| | if (localStorageTheme) { |
| | document.documentElement.setAttribute('data-theme', localStorageTheme); |
| | } |
| | </script> |
| | </head> |
| | <body> |
| | <div class="theme-toggle"> |
| | <button |
| | class="theme-toggle-btn js-theme-toggle" |
| | aria-label="Activate dark mode" |
| | title="Activate dark mode" |
| | > |
| | <!-- |
| | <svg class="light-mode"> |
| | <use xlink:href="#sun"></use> |
| | </svg> |
| | <svg class="dark-mode"> |
| | <use xlink:href="#moon"></use> |
| | </svg> |
| | --> |
| | </button> |
| | </div> |
| | |
| | <script src="app.js"></script> |
| | </body> |
| | </html> |
| | ``` |
| |
|
| | ## CSS Variables |
| |
|
| | ```css |
| | :root { |
| | --bg: #ffffff; |
| | --text: #000000; |
| | } |
| | |
| | [data-theme='dark'] { |
| | --bg: #000000; |
| | --text: #ffffff; |
| | } |
| | ``` |
| |
|
| | ## JavaScript |
| |
|
| | ```js:title=app.js |
| | const themeToggleBtn = document.querySelector('.js-theme-toggle'); |
| | |
| | themeToggleBtn.addEventListener('click', () => onToggleClick()); |
| | |
| | const onToggleClick = () => { |
| | const { theme } = document.documentElement.dataset; |
| | const themeTo = theme && theme === 'light' ? 'dark' : 'light'; |
| | const label = `Activate ${theme} mode`; |
| | |
| | document.documentElement.setAttribute('data-theme', themeTo); |
| | localStorage.setItem('theme', themeTo); |
| | |
| | themeToggleBtn.setAttribute('aria-label', label); |
| | themeToggleBtn.setAttribute('title', label); |
| | }; |
| | ``` |
| |
|
| | ## Resources |
| |
|
| | - <https://css-tricks.com/a-complete-guide-to-dark-mode-on-the-web/> |
| | - <https://css-tricks.com/flash-of-inaccurate-color-theme-fart/> |
| | - <https://mxb.dev/blog/color-theme-switcher/> |
| | - <https://www.joshwcomeau.com/react/dark-mode/> |
| | - <https://web.dev/prefers-color-scheme/> |
| |
|
