Examine source code of 9gag Quick Copy

{
  "description": "Adds a copy button to copy webm link of video post",
  "manifest_version": 2,
  "name": "9GagCopy",
  "version": "1.0.2",
  "homepage_url": "https://9gag.com",
  "icons": {
    "48": "icons/icon-48.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://9gag.com/*",
        "*://*.9gag.com/*"
      ],
      "js": [
        "jquery-3.5.1.min.js",
        "addcopybutton.js"
      ]
    }
  ]
}