Examine source code of SumCopyTables

{
  "manifest_version": 2,
  "name": "SumCopyTables",
  "version": "1.0",
  "description": "Select table cells, rows and columns with your mouse (while pressing shift key) and diplay sum, average, min, max of the selected cells/rows/columns. ",
  "icons": {
    "48": "icons/SumCopyTables-48.png",
    "96": "icons/SumCopyTables-96.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "js": [
        "SCT/jquery.js",
        "SCT/SumCopyTables.js"
      ]
    }
  ]
}