Examine source code of filterify

{
  "author": "mira",
  "manifest_version": 2,
  "name": "filterify",
  "version": "1.0",
  "description": "A Firefox extension for filtering the twitch chat to only see messages from one person only at https://twitch.tv/popout/<username>/chat",
  "icons": {
    "48": "icons/mira.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.twitch.tv/popout/*/chat"
      ],
      "js": [
        "filterify.js"
      ]
    }
  ]
}