Modal Editing in VS Code

ModalEdit is a simple but powerful extension that adds configurable "normal" mode to VS Code. Vim made the concept of modal editing popular among developers and IT professionals. ModalEdit is not a Vim emulation, though. It does not define any default key mappings out-of-the-box. Instead, it encourages you to create your own keyboard layout and customize the editor to suit your preferences.

As in Vim, the goal of the extension is to save your keystrokes and make editing as fast as possible. Unlike most Vim emulators, ModalEdit leverages the built-in features of VS Code. It uses commands provided by VS Code and other extensions. You can build complex operations by arranging commands into sequences. You can define conditional commands that do different things based on editor state. Also, you can map these commands to arbitrarily long keyboard sequences.

Check out the new features in version 1.5 and 1.6, and the updated tutorial. Now you can create even more complex commands than previously. For example, commands that you can repeat by prefixing them with a number, and commands that operate on text inside specified delimiters.

Getting Started

When extension is installed text documents will open in normal mode. The current mode is shown in the status bar. You can switch between modes by clicking the pane in the status bar.

In normal mode keys don't output characters but invoke commands. You can specify these commands in the settings.json file. To edit your user-level settings file, open command palette with Ctrl+Shift+P and look up command Preferences: Open Settings (JSON). If you want the configuration to be project specific, edit the settings.json that is located in the .vscode directory under your project directory.

You might want to skip to the tutorial, if you prefer learning by example. Otherwise keep reading this document.

To define the key mappings used in normal mode, add a property named modaledit.keybindings. You should define at least one binding that will switch the editor to the insert mode, which is the same as VS Code's default mode.

"modaledit.keybindings": {
    "i": "modaledit.enterInsert"
}

When you save the settings.json file, keybindings take effect immediately.

ModalEdit adds a regular VS Code keyboard shortcut for Esc to return back to normal mode. If you wish, you can remap this command to another key by pressing Ctrl+K Ctrl+S.

Selections

ModalEdit does not have a separate selection/visual mode as Vim has. It is possible to select text both in normal mode and insert mode. The [S] text in the status bar indicates when there is text selected.

ModalEdit defines a new command modaledit.toggleSelection which allows you to start selecting text in normal mode without holding down the shift key. This imitates Vim's visual mode.

Configuration

You can define the normal mode commands in four different ways. It is also possible to combine them freely.

Single Command

The simplest way is to map a key to a single command. This has the format:

"<key>": "<command>"

The <key> needs to be a single character and <command> any valid VS Code command. You can see the list of all of the available commands by opening global settings with command Preferences: Open Default Keyboard Shortcuts (JSON).

The example in the previous section maps the i key to the modaledit.enterInsert command.

Commands with Arguments

Some commands take arguments. For example cursorMove which allows you to specify which direction and how much cursor moves. These commands can be executed by defining an object with prefined properties:

"<key>":  {
    "command": "<command>",
    "args": { ... } | "{ ... }"
    "repeat": number | "<JS expression>"
}

The <command> is again a valid VS Code command. The args property contains whatever arguments the command takes. It can be specified as a JSON object or as a string. If the value of the args property is a string, ModalEdit treats it as a JavaScript expression. It evaluates the expression and passes the result to the command. The following variables can be used inside expression strings:

Variable	Type	Description
__file	string	The file name of the document that is edited.
__line	number	The line number where the cursor is currently on.
__col	number	The column number where the cursor is currently on.
__char	string	The character under the cursor.
__selection	string	Currently selected text.
__selecting	boolean	Flag that indicates whether selection is active.
__keySequence	string[]	Array of keys that were pressed to invoke the command.
__keys	string[]	Alias to the __keySequence variable.
__rkeys	string[]	Contains the __keys array reversed. This is handy when you want to access the last characters of the array as they will be first in __rkeys.

The repeat property allows you to run the command multiple times. If the value of the property is a number, it directly determines the repetition count. If it isa string, ModalEdit evaluates it as JS expression and checks if the result is a number. In that case the returned number is used as the repeat count. Note that numbers smaller than 1 will be ignored, and the command is always run at least once.

If returned value is not a number, the expression is treated as a condition that is evaluated after the command has run. The command is repeated as long as the expression returns a truthy value.

Below is an example that maps key o to a command that moves the cursor to the end of line. It also selects the jumped range, if we have selection active.

"o": {
    "command": "cursorMove",
    "args": "{ to: 'wrappedLineEnd', select: __selecting }"
},

Sequence of Commands

To construct more complex operations consisting of multiple steps, you can define command sequences. Commands in a sequence will be run one after another. A sequence is defined as an array.

"<key>": [ <command1>, <command2>, ... ]

In above, <command> can assume any of the supported forms: single command, one with arguments, or conditional command (see below).

The next example maps the f key to a command sequence that first deletes the selected text and then switch to insert mode. It corresponds to the c command in Vim.

"f": [
    "deleteRight",
    "modaledit.enterInsert"
],

Conditional Commands

For even more complex scenarios, you can define commands that run different commands depending on a specified condition. The most common use case for this is to run a different command when selection is active. The format of a conditional commands is:

"<key>":  {
    "condition": "<condition>",
    "<result1>": <command1>,
    "<result2>": <command2>,
    ...
}

Here <condition> can be any valid JavaScript expression. You can use variables listed in the "Commands with Arguments" section in the expression. If the expression evaluates to <result1>, <command1> will be executed, if to <result2>, <command2> will be run, and so forth. If none of the defined properties match the expression result, nothing is done. Commands can be of any kind: a single command, sequence, or command with arguments.

Below is an example that moves cursor one word forward with w key. We use the __selecting variable to determine if a selection is active. If so, we extend the selection using cursorWordStartRightSelect command, otherwise we just jump to next word with cursorWordStartRight.

"w": {
    "condition": "__selecting",
    "true": "cursorWordStartRightSelect",
    "false": "cursorWordStartRight"
},

Binding Key Sequences

When you want to define a multi-key sequence, nest the key bindings. You can define a two key command using the following format.

"<key1>": {
    "<key2>": <command>
},

Again, the <command> can be in any of the forms described above. To invoke the command you first press <key1> in normal mode followed by <key2>.

The example below defines two commands that are bound to key sequences g - f (search forwards) and g - b (search backwards).

"g": {
    "f": {
        "command": "modaledit.search",
        "args": {}
    },
    "b": 
        "command": "modaledit.search",
        "args": {
            "backwards": true
        }
    }
}

Defining Recursive Keymaps

Version 1.5 of ModalEdit introduced the possibility to create recursive keymaps. With this feature you can define arbitrarily long keyboard sequences. This is useful, for example, for creating commands that you can repeat by entering first a number followed by a command key. Keymaps got two new features to enable this functionality.

Key Ranges

You can add multiple characters to a keybinding comma , and dash -. For example, a,b bind both a and b to the same action. You can also add ranges like any numeric character 0-9. The ASCII code of the first character must be smaller than the second one's. You can also combine these notations; for instance, range a,d-f maps keys a, d, e, and f to a same action.

Keymap IDs

By giving keymap a numeric ID, you can refer to it in another (or same) keymap. With key ranges, this allows you to create a binding that can take theoretically infinitely long key sequence. The example below shows how you can define commands like 3w that moves the cursor forward by three words. First we define the commands that moves or select the previous/next word (with keys b and w), and then we create a binding that matches a positive number using key ranges and a recursive keymap. We also use the modaledit.typeNormalKeys command to invoke the existing key bindings and the repeat property to repeat the command.

        "w": {
            "condition": "__selecting",
            "true": "cursorWordStartRightSelect",
            "false": "cursorWordStartRight"
        },
        "b": {
            "condition": "__selecting",
            "true": "cursorWordStartLeftSelect",
            "false": "cursorWordStartLeft"
        },
        "1-9": {
            "id": 1,
            "help": "Enter count followed by [w, b]",
            "0-9": 1,
            "w,b": {
                "command": "modaledit.typeNormalKeys",
                "args": "{ keys: __rkeys[0] }",
                "repeat": "Number(__keys.slice(0, -1).join(''))"
            }
        }

We give the keymap attached to key range 1-9 the id of 1. When that keymap is active pressing key 0-9 will "jump" back to the same keymap. That is designated by the number 1 in the key binding. Only when the user presses some other key we get out of this keymap. If the user presses w or b, we run the command bound to the respective key. We get the repetition count by slicing the all but last character from the __keys array and converting that to a number. The command key is the last item of the __keys array. We can access it more easily using the reversed __rkeys array. The item is first in that array.

The picture below illustrates how keymap and command objects are stored in memory.

It is also possible to jump to another keymap, which enables even more complicated keyboard sequences. The only restriction is that you can only jump to a key binding which is already defined. I.e. you cannot refer to an ID of a keymap that appears later in the configuration.

To better understand how keymaps work behind the scenes check the source documentation.

Another new feature used in the example above is the optional help property in the keymap. The contents of the property is shown in the status bar when the keymap is active. It makes using long keyboard sequences easier by providing a hint what keys you can press next.

Debugging Keybindings

If you are not sure that your bindings are correct, check the ModalEdit's output log. You can find it by opening View - Output and then choosing the ModalEdit from the drop-down menu. Errors in configuration will be reported there. If your configuration is ok, you should see the following message.

Changing Cursors

You can set the cursor shape shown in each mode by changing the following settings.

Setting	Default	Description
insertCursorStyle	line	Cursor shown in insert mode.
normalCursorStyle	block	Cursor shown in normal mode.
searchCursorStyle	underline	Cursor shown when incremental search is on.

The possible values are:

• block
• block-outline
• line
• line-thin
• underline
• underline-thin

Start in Normal Mode

If you want VS Code to be in insert mode when it starts, set the startInNormalMode setting to false. By default, editor is in normal mode when you open it.

Example Configurations

You can find example key bindings here. These are my own settings. The cheat sheet for my keyboard layout is shown below. I have created it in http://www.keyboard-layout-editor.com/. Please note that my keyboard layout is Finnish, so the non-alphanumeric keys might be in strange places.

As you can see, I haven't followed Vim conventions but rather tailored the keyboard layout according to my own preferences. I encourage you to do the same.

In general, you should not try to convert VS Code into a Vim clone. The editing philosophies of Vim and VS Code are quite dissimilar. Targets of Vim operations are defined with special range commands, whereas VS Code's commands operate on selected text. For example, to delete a word in Vim, you first press d to delete and then w for word. In VS Code you first select the word (with W or e key in my configuration) then you delete the selection with d key.

To better understand the difference, check out Kakoune editor's documentation. ModalEdit extends VS Code with normal mode editing, so you have more or less the same capabilities as in Kakoune.

Additional VS Code Commands

ModalEdit adds few useful commands to VS Code's repertoire. They help you create more Vim-like workflow for searching and navigation.

Switching between Modes

Use the following commands to change the current editor mode. None of the commands require any arguments.

Command	Description
modaledit.toggle	Toggles between modes
modaledit.enterNormal	Switches to normal mode
modaledit.enterInsert	Switches to insert mode
modaledit.toggleSelection	Toggles selection mode on or off. Selection mode is implicitly on whenever editor has text selected
modaledit.cancelSelection	Cancel selection mode and clear selection.

Incremental Search

The standard search functionality in VS Code is quite clunky as it opens a dialog which takes you out of the editor. To achieve more fluid searching experience ModalEdit provides incremental search commands that mimic Vim's corresponding operations.

modaledit.search

Starts incremental search. The cursor is changed to indicate that editor is in search mode. Normal mode commands are suppressed while incremental search is active. Just type the search string directly without leaving the editor. You can see the searched string in the status bar as well as the search parameters.

The command takes following arguments. All of them are optional.

Argument	Type	Default	Description
backwards	boolean	false	Search backwards. Default is forwards
caseSensitive	boolean	false	Search is case-sensitive. Default is case-insensitive
acceptAfter	number	undefined	Accept search automatically after x characters has been entered. This helps implementing quick one or two character search operations.
selectTillMatch	boolean	false	Select the range from current position till the match instead of just the match. Useful with acceptAfter to quickly extend selection till the specified character(s).
typeAfterAccept	string	undefined	Allows to run normal mode commands through key bindings (see modaledit.typeNormalKeys command) after successful search. The argument can be used to enter insert mode, or clear selection after search, for example. The same command sequence is run also after modaledit.nextMatch and modaledit.previousMatch commands. I.e. the argument persists the same way as the search direction.

modaledit.cancelSearch

Cancels the incremental search, returns the cursor to the starting position, and switches back to normal mode.

modaledit.deleteCharFromSearch

Deletes the last character of the search string. By default the backspace key is bound to this command when ModalEdit is active and in search mode.

modaledit.nextMatch

Moves to the next match and selectes it. Which way to search depends on the search direction.

modaledit.previousMatch

Moves to the previous match and selectes it. Which way to search depends on the search direction.

Bookmarks

To quickly jump inside documents ModalEdit provides two bookmark commands:

• modaledit.defineBookmark stores the current position in a bookmark, and
• modaledit.goToBookmark jumps to the given bookmark.

Both commands take one argument which contains the bookmark index. It can be any number, so you can define unlimited number of bookmarks. If the argument is omitted, default value 0 is assumed.

{
    "command": "modaledit.defineBookmark",
    "args": {
        "bookmark": 0
    }
}

Quick Snippets

Snippets come in handy when you need to insert boilerplate text. However, the problem with snippets is that very seldom one bothers to create a new one. If a snippet is used only a couple of times in a specific situation, the effort of defining it nullifies the advantage.

With ModalEdit, you can create snippets quickly by selecting a region of text and invoking command modaledit.defineQuickSnippet. You can assign the snippet to a register by specifying its index as an argument.

{
    "command": "modaledit.defineQuickSnippet",
    "args": {
        "snippet": 1
    }
}

Use the modaledit.insertQuickSnippet command to insert the defined snippet at the cursor position. It takes the same argument as modaledit.defineQuickSnippet.

A snippet can have arguments or placeholders which you can fill in after inserting it. These are written as $1, $2, ... inside the snippet. You can quickly define the arguments with the modaledit.fillSnippetArgs command. First multi-select all the arguments (by pressing Alt while selecting with a mouse), then run the command. After that, select the snippet itself and run the modaledit.defineQuickSnippet command.

In the following example key sequence q - a fills snippet arguments, q - w - 1 defines snippet in register 1, and q - 1 inserts it.

It is usually a good idea to run editor.action.formatDocument after inserting a snippet to clean up whitespace. You can do this automatically adding it to the command sequence.

"q": {
    "1": [
        {
            "command": "modaledit.insertQuickSnippet",
            "args": {
                "snippet": 1
            }
        },
        "editor.action.formatDocument"
    ],
}

Invoking Key Bindings

The new command modaledit.typeNormalKeys invokes commands through key bindings. Calling this command with a key sequence has the same effect as pressing the keys in normal mode. This allows you to treat key bindings as subroutines that can be called using this command.

The command has one argument keys which contains the key sequence as string. Assuming that keys k and u are bound to some commands, the following example runs them both one after another.

{
    "command": "modaledit.typeNormalKeys",
    "args": {
        "keys": "ku"
    }
}

Selecting Text Between Delimiters

The modaledit.selectBetween command helps implement advanced selection operations. The command takes as arguments two strings/regular expressions that delimit the text to be selected. Both of them are optional, but in order for the command to do anything one of them needs to be defined. If the from argument is missing, the selection goes from the cursor position forwards to the to string. If the to is missing the selection goes backwards till the from string. In addition to these parameters, the command has four flags:

• If the regex flag is on, from and to strings are treated as regular expressions in the search.
• The inclusive flag tells if the delimiter strings are included in the selection or not. By default the delimiter strings are not part of the selection.
• The caseSensitive flag makes the search case-sensitive. When this flag is missing or false the search is case-insensitive.
• By default the search scope is the current line. If you want search inside the whole document, set the docScope flag.

Below is an example that selects all text inside quotation marks. For more advanced examples check the tutorial.

{
    "command": "modaledit.selectBetween",
    "args": { 
        "from": "(", 
        "to": ")"
    }
}

Repeat Last Change

modaledit.repeatLastChange command repeats the last command (sequence) that caused text in the editor to change. It corresponds to the dot . command in Vim. The command takes no arguments.

Acknowledgements

I was using the Simple Vim extension for a long time, but was never fully happy with it. It shares the idea of being a simple extension reusing VS Code's functionality, but it is sorely lacking in configurability. If you don't like its default key mappings, you are out of luck.

Then I found extension called Vimspired which has a really great idea for implementing modal editing: just add a section in the settings.json which contains the keymap for normal mode. This allows you to mimic Vim behavior, if you wish to do so, or take a completely different approach. For example, don't use h, j, k, l keys to move the cursor but w, a, s, d keys instead.

I really like Vimspired, but still wanted to change some of its core behavior and add many additional features. I didn't want to harass the author with extensive pull requests, so I decided to implement my own take of the theme. I shameleslly copied the core parts of Vimspired and then changed them beyond recognition. Anyway, credit goes to Brian Malehorn for coming up with the great idea and helping me jump start my project.