Karabiner Elements: Caps Lock + I/J/K/L to Arrow Keys (a la Pok3r)

instructions.md

Instructions

1. Install Karabiner Elements
2. Open your karabiner.json file (it will be in ~/.config/karabiner/karabiner.json).
3. Find complex_modifications. It will have a key rules that takes a list ("rules": [...]).
4. Inside the square brackets, paste this:

{
    "description": "Change Caps Lock + I/J/K/L to Arrow Keys",
    "manipulators": [
        {
            "from": {
                "key_code": "caps_lock"
            },
            "to": [
                {
                    "set_variable": {
                        "name": "caps_arrows_mode",
                        "value": 1
                    }
                }
            ],
            "to_after_key_up": [
                {
                    "set_variable": {
                        "name": "caps_arrows_mode",
                        "value": 0
                    }
                }
            ],
            "to_if_alone": [
                {
                    "key_code": "caps_lock"
                }
            ],
            "type": "basic"
        },
        {
            "conditions": [
                {
                    "name": "caps_arrows_mode",
                    "type": "variable_if",
                    "value": 1
                }
            ],
            "from": {
                "key_code": "j",
                "modifiers": {
                    "optional": [
                        "any"
                    ]
                }
            },
            "to": [
                {
                    "key_code": "left_arrow"
                }
            ],
            "type": "basic"
        },
        {
            "conditions": [
                {
                    "name": "caps_arrows_mode",
                    "type": "variable_if",
                    "value": 1
                }
            ],
            "from": {
                "key_code": "k",
                "modifiers": {
                    "optional": [
                        "any"
                    ]
                }
            },
            "to": [
                {
                    "key_code": "down_arrow"
                }
            ],
            "type": "basic"
        },
        {
            "conditions": [
                {
                    "name": "caps_arrows_mode",
                    "type": "variable_if",
                    "value": 1
                }
            ],
            "from": {
                "key_code": "i",
                "modifiers": {
                    "optional": [
                        "any"
                    ]
                }
            },
            "to": [
                {
                    "key_code": "up_arrow"
                }
            ],
            "type": "basic"
        },
        {
            "conditions": [
                {
                    "name": "caps_arrows_mode",
                    "type": "variable_if",
                    "value": 1
                }
            ],
            "from": {
                "key_code": "l",
                "modifiers": {
                    "optional": [
                        "any"
                    ]
                }
            },
            "to": [
                {
                    "key_code": "right_arrow"
                }
            ],
            "type": "basic"
        }
    ]
}

For anyone coming here looking for the answer to modifier keys: this is the fix needed to the above -- Change the first manipulators line to:

            "manipulators": [
                    {
                      "from": {
                        "key_code": "caps_lock",
                        "modifiers": {
                          "optional": [
                            "any"
                          ]
                        }
                      },

it works. thank you very much

since my caps lock has been used for vim. i now use the left option key. here is the code for anyone's need.

{
    "description": "Change Option + H/J/K/L to Arrow Keys",
    "manipulators": [
        {
            "from": { "key_code": "left_option" },
            "to": [
                {
                    "set_variable": {
                        "name": "option_arrows_mode",
                        "value": 1
                    }
                }
            ],
            "to_after_key_up": [
                {
                    "set_variable": {
                        "name": "option_arrows_mode",
                        "value": 0
                    }
                }
            ],
            "type": "basic"
        },
        {
            "conditions": [
                {
                    "name": "option_arrows_mode",
                    "type": "variable_if",
                    "value": 1
                }
            ],
            "from": {
                "key_code": "h",
                "modifiers": { "optional": ["any"] }
            },
            "to": [{ "key_code": "left_arrow" }],
            "type": "basic"
        },
        {
            "conditions": [
                {
                    "name": "option_arrows_mode",
                    "type": "variable_if",
                    "value": 1
                }
            ],
            "from": {
                "key_code": "j",
                "modifiers": { "optional": ["any"] }
            },
            "to": [{ "key_code": "down_arrow" }],
            "type": "basic"
        },
        {
            "conditions": [
                {
                    "name": "option_arrows_mode",
                    "type": "variable_if",
                    "value": 1
                }
            ],
            "from": {
                "key_code": "k",
                "modifiers": { "optional": ["any"] }
            },
            "to": [{ "key_code": "up_arrow" }],
            "type": "basic"
        },
        {
            "conditions": [
                {
                    "name": "option_arrows_mode",
                    "type": "variable_if",
                    "value": 1
                }
            ],
            "from": {
                "key_code": "l",
                "modifiers": { "optional": ["any"] }
            },
            "to": [{ "key_code": "right_arrow" }],
            "type": "basic"
        }
    ]
}