Examine source code of BRAINS-19

{
  "browser_specific_settings": {
    "gecko": {
      "id": "BRAINS-19-Firefox-0.1.xpi-raegun@gammarae.design"
    }
  },
  "manifest_version": 2,
  "name": "BRAINS-19",
  "description": "Replaces mentions of COVID-19 or Coronavirus on a webpage with 'Zombie Apocalypse' or 'Zombie Infection' instead.",
  "version": "0.4",
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "jquery-3.4.1.slim.min.js",
        "findAndReplaceDOMText.js",
        "braaaaaaains.js"
      ]
    }
  ],
  "browser_action": {
    "default_icon": "noooo_braaaaaaaaains-38.png"
  },
  "background": {
    "scripts": [
      "bgraaaaaaaaaains.js"
    ]
  },
  "permissions": [
    "storage",
    "activeTab"
  ]
}