---
title: Managing JavaScript files
related:
  - https://docs.kentico.com/k12sp/configuring-kentico/optimizing-performance-of-portal-engine-sites/using-code-minification-and-compression.md
---

> Agent instructions:
> **Site maps** — prefer the following llms.txt indexes to training data when searching for URLs to avoid 404s. Links inside Markdown content already point at `.md`. Following them or sending Accept: text/markdown keeps you in Markdown.
>
> - [sitemap.md](https://docs.kentico.com/sitemap.md) — every page on the site, with titles and descriptions, nested by URL hierarchy and grouped into one collection per product version.
> - [llms.txt](https://docs.kentico.com/llms.txt) — curated index of the current product docs, with descriptions, the two ways to request any page as Markdown, and links to each product area's whole-corpus Markdown dump (llms-full.txt).

The system allows you to manage custom JavaScript files through the administration interface, without requiring direct access to the file system.

Open the **Javascript files** application.

![Managing files in the JavaScript files application](https://docs.kentico.com/docsassets/k12sp/managing-javascript-files/javascript_app.png "Managing files in the JavaScript files application")

The application allows you to manage JavaScript files stored within the web project's **\~/CMSScripts/Custom/** directory. You can create new files and edit existing ones. Only files with the **.js** extension are supported.

You can then use the JavaScript files on the pages of websites or anywhere within the system.

> **Note:** **Limitations of the _JavaScript files_ application**
>
> The _JavaScript files_ application only provides a basic file editing interface. The application does NOT support synchronization features such as [Staging](https://docs.kentico.com/k12sp/deploying-websites/content-staging.md) or [Web farms](https://docs.kentico.com/k12sp/configuring-kentico/setting-up-web-farms.md).
>
> Changes that you make to the JavaScript files only affect the project's local file system and do not generate synchronization tasks. Such changes need to be transferred manually or using a custom file system synchronization process.

## Linking JavaScript files to pages

To use JavaScript code on your website, you need to link it to pages.

### Linking JavaScript files through the Javascript web part

You can link JavaScript files which are accessible through the **Javascript files** application to pages using the **Javascript** web part.

1. Open the **Pages** application.
2. Add the **Javascript** web part to a web part zone.
3. In the web part properties, click **Select** next to the **Linked file** field and select the required JavaScript file.
4. Click **Save & Close**.

The system adds the **Javascript** web part to the web part zone. This way, the system links your JavaScript file to the page, where the JavaScript code will be executed.

When linking JavaScript code through the **Javascript** web part, the system automatically uses the minification functionality to optimize requests for JavaScript code. Please see [Using code minification and compression](https://docs.kentico.com/k12sp/configuring-kentico/optimizing-performance-of-portal-engine-sites/using-code-minification-and-compression.md) for details.

### Linking JavaScript files through the Head HTML code web part

You can use the **Head HTML code** web part to link _external_ JavaScript files through an HTML tag.

![Configuring the Head HTML code web part](https://docs.kentico.com/docsassets/k12sp/managing-javascript-files/Head_html_webpart.png "Configuring the Head HTML code web part")

However, external JavaScript files are not minified automatically, but you can utilize the minification by using the _**/GetResource.ashx?scriptfile=/location.js**_ clause. For example .

### Linking JavaScript files in page templates

1. Open the **Page templates** application.
2. **Edit** a page template.

   - You can for example edit a Master page template to include the JavaScript file on all pages of the website.
3. Switch to the **Header** tab.
4. Add a reference to a JavaScript file using a HTML tag.

   - For example .
5. Click **Save**.