Examine source code of Smart Text

{
  "manifest_version": 2,
  "name": "Smart Text",
  "version": "1.4.1",
  "developer": {
    "name": "MetroWind",
    "url": "https://darksair.org/"
  },
  "homepage_url": "https://github.com/MetroWind/smart-text-firefox",
  "description": "Smart text substitutions on-the-fly when you input. Replace straight quotes with curly quotes (smart quotes), dumb dashes with en-dash/em-dash (smart dashes), 3 dots with ellipsis, and 6 dots with 2 mid-line ellipsis (used in Chinese). Right now you need to disable the addon to stop substitution. I’ll add an switch later.",
  "icons": {
    "48": "icons/smart.svg",
    "96": "icons/smart.svg"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "smart.js"
      ]
    }
  ]
}