Examine source code of Kirka.io global chat item prices

{
  "manifest_version": 2,
  "name": "Kirka.io global chat item prices",
  "version": "0.57",
  "description": "Add price next to [Items] in kirka.io Global chat. Add /trade offer statistics, my total value, your total value and difference if a trade would be accepted in a status: result. Made by skywalk and CarrySheriff.",
  "author": "SheriffCarry, skywalk",
  "homepage_url": "https://api.github.com/repos/SheriffCarry/KirkaScripts/contents/Userscript/globalChatItemPricesAndTradeStats.js",
  "applications": {
    "gecko": {
      "id": "skywalk818@gmail.com"
    }
  },
  "icons": {
    "48": "icon.png"
  },
  "options_ui": {
    "page": "options.html",
    "open_in_tab": false
  },
  "content_scripts": [
    {
      "matches": [
        "*://kirka.io/*"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_start"
    }
  ],
  "permissions": [
    "storage",
    "*://stonkch.art/*"
  ]
}