Examine source code of Eslfast Helper

{
  "manifest_version": 2,
  "name": "Eslfast Helper",
  "version": "1.2.0",
  "description": "Improves user experience on https:/rong-chang.com and https://eslfast.com",
  "content_scripts": [
    {
      "matches": [
        "*://*.eslfast.com/*",
        "*://*.rong-chang.com/*"
      ],
      "js": [
        "index.js"
      ],
      "css": [
        "style.css"
      ]
    }
  ]
}