Examine source code of B

{
  "name": "🅱️",
  "description": "Replace the letter B with the 🅱️ emoji everywhere.",
  "version": "3.1",
  "author": "Daniel Ting",
  "manifest_version": 2,
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "all_frames": true,
      "js": [
        "TextObserver.min.js",
        "main.js"
      ],
      "run_at": "document_end"
    }
  ],
  "permissions": [
    "storage",
    "tabs"
  ],
  "icons": {
    "128": "./assets/b.png"
  },
  "browser_action": {},
  "browser_specific_settings": {
    "gecko": {
      "id": "b@example.com"
    }
  }
}