Examine source code of Open Right Beside

{
  "author": "igorlogius",
  "homepage_url": "https://github.com/igorlogius/webextensions/tree/main/sources/open-right-beside",
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "icons": {
    "128": "icon.png"
  },
  "description": "Open new tabs right beside their opener (aka. parent) tab or beside the currently active tab if no parent exists",
  "manifest_version": 2,
  "name": "Open Right Beside",
  "permissions": [
    "tabs",
    "tabGroups"
  ],
  "version": "1.0.14",
  "browser_specific_settings": {
    "gecko": {
      "id": "{34c70c1d-2b58-4942-a706-bf0d73455896}"
    }
  }
}