# Install deno for yt-dlp JavaScript runtime

## Problem

yt-dlp now requires a JavaScript runtime for full YouTube extraction. Without it, you get this warning:

```
WARNING: No supported JavaScript runtime could be found.
YouTube extraction without a JS runtime has been deprecated, and some formats may be missing.
```

## Solution

Install deno (the default supported runtime):

```bash
sudo pacman -S deno
```

## Why

YouTube uses JavaScript for some format extraction. Without a JS runtime, yt-dlp may not be able to access all video formats or could fail on certain videos.

See: https://github.com/yt-dlp/yt-dlp/wiki/EJS