This project is a small, zero-dependency polyfill for the HTML switch control <input type="checkbox" switch>.

The polyfill provides a visual switch-style control for checkboxes using the switch attribute, and gracefully defers to native browser support where available.

Install the package as a dependency (for example, in a static site or simple web app):

npm install input-switch-polyfill

This package ships the following files:

• input-switch-polyfill.js – the polyfill logic
• input-switch-polyfill.css – the accompanying styles

<script type="module">
  if (!('switch' in HTMLInputElement.prototype)) {
    await import('https://unpkg.com/input-switch-polyfill/input-switch-polyfill.js');
  }
</script>

Alternatively, copy input-switch-polyfill.js and input-switch-polyfill.css into your project (for example, next to your index.html) and reference them directly.

Conditionally load the polyfill as an ES module to only apply it when the browser does not already support input[switch] natively, and hide the switch input temporarily to give it a chance to load. This loading pattern prevents flash of unstyled content (FOUC).

<style>
  @keyframes hideBriefly {
    0%,
    100% {
      visibility: hidden;
    }
  }

  label:has(input[switch]),
  input[switch] {
    animation: hideBriefly 2s;
  }
</style>

<noscript>
  <style>
    label:has(input[switch]),
    input[switch] {
      animation: none;
    }
  </style>
</noscript>

<script type="module">
  if (!('switch' in HTMLInputElement.prototype)) {
    await import('./input-switch-polyfill.js');
  } else {
    document.head.insertAdjacentHTML(
      'beforeend',
      `<style>label:has(input[switch]),input[switch]{animation:none;}</style>`
    );
  }
</script>

Then, in your HTML, use checkboxes with the switch attribute:

<label>
  Default
  <input type="checkbox" switch />
</label>

<label>
  Accent color red
  <input type="checkbox" switch style="accent-color: red" />
</label>

<label>
  Accent color #00ff00 default checked
  <input type="checkbox" switch checked style="accent-color: #00ff00" />
</label>

This mirrors the usage in index.html in this repository.

The polyfill reads the computed accent-color of each input[type="checkbox"][switch] and maps it to a CSS custom property --switch-accent. You can:

• Rely on inherited accent-color
• Set accent-color inline (as in the examples above)
• Or set accent-color via CSS rules

The provided input-switch-polyfill.css uses --switch-accent to style the visual switch.

You can see a demo of this polyfill right in your browser.

Clone the repository and install dependencies:

git clone https://github.com/tomayac/input-switch-polyfill.git
cd input-switch-polyfill
npm install

Start a simple static server (as defined in package.json):

npm start

Then open index.html in your browser (or follow the URL printed by the dev server) to see the demo, which corresponds to the usage shown above.

Licensed under the Apache License, Version 2.0. See LICENSE for details.