Karabiner Elements tab switching shortcuts

gistfile1.txt

{
  "description": "Tab switching: Change Cmd-j to Cmd-Alt-left",
  "manipulators": [
    {
      "from": {
        "key_code": "j",
        "modifiers": {
          "mandatory": [
            "command"
          ]
        }
      },
      "to": [
        {
          "key_code": "left_arrow",
          "modifiers": [
            "command",
            "option"
          ]
        }
      ],
      "type": "basic"
    }
  ]
},
{
  "description": "Tab switching: Change Cmd-k to Cmd-Alt-right",
  "manipulators": [
    {
      "from": {
        "key_code": "k",
        "modifiers": {
          "mandatory": [
            "command"
          ]
        }
      },
      "to": [
        {
          "key_code": "right_arrow",
          "modifiers": [
            "command",
            "option"
          ]
        }
      ],
      "type": "basic"
    }
  ]
},