Examine source code of Table Sum Inserter

{
  "manifest_version": 2,
  "name": "Table Sum Inserter",
  "description": "Instantly adds a new row to any HTML table displaying the sum of each numeric column. Just click a button, and the totals are calculated and inserted—no more manual summing or copying to spreadsheets! Perfect for data analysts, students, and anyone working with tabular web data",
  "version": "0.1.0",
  "permissions": [
    "activeTab"
  ],
  "browser_action": {
    "default_icon": {
      "512": "summifyAllTables.png"
    }
  },
  "background": {
    "persistent": false,
    "scripts": [
      "summifyAllTables.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{4c5781f2-45e6-4f86-9bc4-63327d9c6f06}"
    }
  }
}