Alt+Number to switch tabs

manifest.json

{
  "author": "Emilio Cobos Álvarez <[email protected]>",
  "background": {
    "scripts": [
      "ctrlnumber.js"
    ]
  },
  "commands": {
    "switch-tab-1": {
      "description": "Switch to the first tab",
      "suggested_key": {
        "default": "Alt+1"
      }
    },
    "switch-tab-2": {
      "description": "Switch to the second tab",
      "suggested_key": {
        "default": "Alt+2"
      }
    },
    "switch-tab-3": {
      "description": "Switch to the third tab",
      "suggested_key": {
        "default": "Alt+3"
      }
    },
    "switch-tab-4": {
      "description": "Switch to the fourth tab",
      "suggested_key": {
        "default": "Alt+4"
      }
    },
    "switch-tab-5": {
      "description": "Switch to the fifth tab",
      "suggested_key": {
        "default": "Alt+5"
      }
    },
    "switch-tab-6": {
      "description": "Switch to the sixth tab",
      "suggested_key": {
        "default": "Alt+6"
      }
    },
    "switch-tab-7": {
      "description": "Switch to the seventh tab",
      "suggested_key": {
        "default": "Alt+7"
      }
    },
    "switch-tab-8": {
      "description": "Switch to the eighth tab",
      "suggested_key": {
        "default": "Alt+8"
      }
    },
    "switch-tab-9": {
      "description": "Switch to the last tab",
      "suggested_key": {
        "default": "Alt+9"
      }
    }
  },
  "description": "This extension adds keyboard shortcuts to switch tabs. Alt+1 switches to the first tab, Alt+2 switches to the second tab, and so on. Alt+9 switches to the last tab. This matches the shortcuts on Linux",
  "homepage_url": "https://github.com/emilio/firefox-altnumber#readme",
  "manifest_version": 2,
  "name": "Alt+Number to switch tabs",
  "short_name": "Alt+Number",
  "version": "1.0.0"
}