Examine source code of KeyboardSounder

{
  "manifest_version": 3,
  "name": "KeyboardSounder",
  "version": "1.0",
  "description": "it can achieve the sound effect of a mechanical keyboard when typing on web pages in the browser",
  "browser_specific_settings": {
    "gecko": {
      "id": "laweilan@gmail.com"
    }
  },
  "permissions": [
    "scripting",
    "tabs"
  ],
  "host_permissions": [
    "<all_urls>"
  ],
  "action": {
    "default_popup": "popup.html"
  },
  "background": {
    "type": "module",
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "icons": {
    "16": "icon16.png",
    "32": "icon32.png",
    "48": "icon48.png",
    "64": "icon64.png",
    "128": "icon128.png"
  }
}