Examine source code of NexusModRewards

{
  "manifest_version": 2,
  "name": "NexusModRewards",
  "version": "1.0",
  "description": "Adds some useful stats to Nexusmods Rewards page.",
  "content_scripts": [
    {
      "matches": [
        "*://*.nexusmods.com/modrewards*"
      ],
      "js": [
        "NexusModRewards.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{ffbc18af-0582-4fd1-a0e6-67801bc4a10e}"
    }
  }
}