Examine source code of Sort by Score Button

{
  "manifest_version": 3,
  "name": "Sort by Score Button",
  "version": "1.0",
  "description": "Adds a button to insert 'sort:score' in rule34.xxx and gelbooru.com search bars.",
  "permissions": [
    "scripting"
  ],
  "host_permissions": [
    "*://rule34.xxx/*",
    "*://gelbooru.com/*"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://rule34.xxx/*",
        "*://gelbooru.com/*"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "icons": {
    "48": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "sortscorebutton@yourname.dev"
    }
  }
}