Examine source code of hold-my-timetracking

{
  "manifest_version": 2,
  "name": "hold-my-timetracking",
  "version": "1.0.2",
  "description": "Tired of tracking your time? Let's this extension do it for you",
  "icons": {
    "48": "icons/hold.ico"
  },
  "content_scripts": [
    {
      "matches": [
        "https://app.holded.com/employees/timetracking"
      ],
      "js": [
        "hold-my-timetracking.js"
      ]
    }
  ]
}