Examine source code of Em Dash Highlighter

{
  "$schema": "https://json.schemastore.org/chrome-manifest",
  "name": "Em dash highlighter",
  "version": "0.0.1",
  "manifest_version": 3,
  "description": "Highlight em dashes like a pro.",
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "scan.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "icons": {
    "48": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "@emdashhighlighter",
      "strict_min_version": "58.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}