> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify-han-update-changelogs.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Custom JS

> Add JavaScript functionality globally

<Check>
  Custom JS is available as an add-on to the [pro plan](https://mintlify.com/pricing).
</Check>

Custom JS allows you to add custom executable code globally. It is the equivalent of adding a `<script>` tag with JS code into every page.

## Adding Custom JavaScript

Any `.js` file inside the content directory of your docs will be included in every documentation page. For example, you can add the following `ga.js` file to enable [Google Analytics](https://marketingplatform.google.com/about/analytics) across the entire documentation.

```js
window.dataLayer = window.dataLayer || [];
function gtag() {
  dataLayer.push(arguments);
}
gtag('js', new Date());

gtag('config', 'TAG_ID');
```

<Warning>
  Please use with caution to not introduce security vulnerabilities.
</Warning>