npm package: @mahozad/theme-switch
Description: Animated toggle button to switch between light/dark/system theme.
Author: Mahdi Hosseinzadeh
Latest version: 1.5.2

[![Tests workflow](https://img.shields.io/github/workflow/status/mahozad/theme-switch/CI?label=Tests&logo=github)](https://github.com/mahozad/theme-switch/actions/workflows/ci.yml)
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[![Minified size](https://img.shields.io/github/size/mahozad/theme-switch/dist/theme-switch.min.js?label=Minified%20size)](https://unpkg.com/@mahozad/theme-switch)
[![Published on webcomponents.org](https://img.shields.io/badge/webcomponents.org-published-9351dc.svg)](https://www.webcomponents.org/element/@mahozad/theme-switch)

<div align="center">

![Animated icon](https://raw.githubusercontent.com/mahozad/theme-switch/main/icon.svg)

</div>

# HTML light/dark/system theme switch button

This is an animated [custom HTML element](https://developer.mozilla.org/en-US/docs/Web/Web_Components/Using_custom_elements)
which toggles between light theme, dark theme, and automatic theme (OS theme).
It adds a custom attribute (`data-theme`) to the `html` element of your page.
You can style your page the way you like based on the value of that attribute.

See the [demo page](https://mahozad.ir/theme-switch/) and scroll below for an [example](#styling-a-page-based-on-the-theme).

## Installing and using the library

  - ### Regular HTML pages
    ```html
    <script src="https://unpkg.com/@mahozad/theme-switch"></script>
    ```
  - ### Node.js and npm
    ```shell
    npm install --save @mahozad/theme-switch
    ```
    ```html
    <script src="node_modules/@mahozad/theme-switch/dist/theme-switch.min.js"></script>
    ```

  - ### Angular and more
    For Angular framework and more details about the above installation methods see the [wiki](https://github.com/mahozad/theme-switch/wiki).

After installing the library, use the element like this (make sure to include the end tag):

```html
<theme-switch></theme-switch>
```

## Styling the switch element

A custom element is no different from the built-in elements of HTML.  
Use and style it however you want just like you would use and style a regular element:

```css
theme-switch {
  width: 64px;
  padding: 8px;
  background: #888;
  
  /* There is a special property called --theme-switch-icon-color
   * which you can set, to change the color of the icon in the switch */
  --theme-switch-icon-color: #aabbcc;
}
```

## Styling a page based on the theme

In your CSS stylesheet, specify your desired styles for light and dark themes.
One way is to define [custom CSS properties](https://developer.mozilla.org/en-US/docs/Web/CSS/Using_CSS_custom_properties)
for your colors, sizes, etc. and redefine them (if needed) with new values for the other theme:

```css
/* These are applied for the default (light) theme */
/* (or when the toggle is auto, and the OS theme is light) */
html {
  --my-page-background-color: #fff;
  --my-icons-color: #000;
  --my-primary-color: red;
}

/* These are applied for the dark theme */
/* (or when the toggle is auto, and the OS theme is dark) */
/* If a property has the same value for both light and dark themes, no need to redeclare it here */
html[data-theme="dark"] {
  --my-page-background-color: #112233;
  --my-icons-color: #efefef;
}

body {
  background: var(--my-page-background-color);
}
```

## Misc

<details>

<summary>Click here to expand</summary>

The switch element fires (triggers) a custom event called `themeToggle` every time it is toggled (clicked).
You can listen and react to it if you want:

```javascript
document.addEventListener("themeToggle", event => {
  console.log(`Old theme: ${ event.detail.oldState }`);
  console.log(`New theme: ${ event.detail.newState }`);
  // More operations...
});
```

---

This widget was inspired by [this YouTube video](https://youtu.be/kZiS1QStIWc)
and [this library](https://github.com/GoogleChromeLabs/dark-mode-toggle).

---

See [this article](https://css-tricks.com/web-components-are-easier-than-you-think/)
which is about creating HTML custom elements.

See the icon for switching themes (located in the top right corner) on
[Google Fonts site](https://fonts.google.com/icons).  
Also see [this site](https://rastikerdar.github.io/vazirmatn).

See [this article](https://css-tricks.com/a-complete-guide-to-dark-mode-on-the-web)
for implementing dark/light theme on sites.

See [this post](https://stackoverflow.com/q/56300132/8583692) for how to override
dark/light theme for a site.

See [this comprehensive GitHub repo](https://github.com/mateusortiz/webcomponents-the-right-way) about custom elements.

---

### Similar libraries
  - [Dark Mode Toggle](https://github.com/H0rn0chse/dark-mode-toggle)
  - [\<dark-mode-toggle>](https://github.com/GoogleChromeLabs/dark-mode-toggle)
  - [\<color-scheme-button>](https://github.com/CICCIOSGAMINO/color-scheme-button)
  - [\<theme-toggle>](https://github.com/mothepro/theme-toggle)
  - [Binary theme switcher component](https://github.com/diegosanchezp/theme-switcher-component)

---

TODO:
  - Try to add the library to [rufus site](https://github.com/pbatard/rufus-web)
  - Try to add the library to [jest site](https://github.com/facebook/jest) (probably its `docs/` directory. see [this PR](https://github.com/facebook/jest/pull/11021))
  - Try to add the library to [MDN site](https://developer.mozilla.org/en-US/)
  - Try to add the library to [docusaurus](https://github.com/facebook/docusaurus)
  - Try to add the library to [dokka](https://github.com/Kotlin/dokka)
  - Try to add the library to [mkdocs-material](https://github.com/squidfunk/mkdocs-material)
  - See [chrome auto dark feature for android](https://developer.chrome.com/blog/new-in-chrome-98/#autodark-opt-out)

</details>