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Nvim Node.js client and plugin host


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Currently tested for node >= 10


Install the neovim package globally using npm.

npm install -g neovim

A global package is required for neovim to be able to communicate with a plugin.


This package exports a single attach() function which takes a pair of write/read streams and invokes a callback with a Nvim API object.


const cp = require('child_process');
const attach = require('neovim').attach;

const nvim_proc = cp.spawn('nvim', ['-u', 'NONE', '-N', '--embed'], {});

// Attach to neovim process
(async function() {
  const nvim = await attach({ proc: nvim_proc });
  const windows = await;

  // expect(windows.length).toEqual(4);
  // expect(windows[0] instanceof nvim.Window).toEqual(true);
  // expect(windows[1] instanceof nvim.Window).toEqual(true);

  nvim.window = windows[2];
  const win = await nvim.window;

  // expect(win).not.toEqual(windows[0]);
  // expect(win).toEqual(windows[2]);

  const buf = await nvim.buffer;
  // expect(buf instanceof nvim.Buffer).toEqual(true);

  const lines = await buf.lines;
  // expect(lines).toEqual(['']);

  await buf.replace(['line1', 'line2'], 0);
  const newLines = await buf.lines;
  // expect(newLines).toEqual(['line1', 'line2']);


Writing a Plugin

A plugin can either be a file or folder in the rplugin/node directory. If the plugin is a folder, the main script from package.json will be loaded.

The plugin should export a function which takes a NvimPlugin object as its only parameter. You may then register autocmds, commands and functions by calling methods on the NvimPlugin object. You should not do any heavy initialisation or start any async functions at this stage, as nvim may only be collecting information about your plugin without wishing to actually use it. You should wait for one of your autocmds, commands or functions to be called before starting any processing.

console has been replaced by a winston interface and console.log will call



This is the nvim api object you can use to send commands from your plugin to nvim.

  NvimPlugin.setOptions(options: NvimPluginOptions);

  interface NvimPluginOptions {
    dev?: boolean;
    alwaysInit?: boolean;

Set your plugin to dev mode, which will cause the module to be reloaded on each invocation. alwaysInit will always attempt to attempt to re-instantiate the plugin. e.g. your plugin class will always get called on each invocation of your plugin's command.

  NvimPlugin.registerAutocmd(name: string, fn: Function, options: AutocmdOptions): void;
  NvimPlugin.registerAutocmd(name: string, fn: [any, Function], options: AutocmdOptions): void;

  interface AutocmdOptions {
    pattern: string;
    eval?: string;
    sync?: boolean;

Registers an autocmd for the event name, calling your function fn with options. Pattern is the only required option. If you wish to call a method on an object you may pass fn as an array of [object, object.method].

By default autocmds, commands and functions are all treated as asynchronous and should return Promises (or should be async functions).

  NvimPlugin.registerCommand(name: string, fn: Function, options?: CommandOptions): void;
  NvimPlugin.registerCommand(name: string, fn: [any, Function], options?: CommandOptions): void;

  interface CommandOptions {
    sync?: boolean;
    range?: string;
    nargs?: string;

Registers a command named by name, calling function fn with options. This will be invoked from nvim by entering :name in normal mode.

  NvimPlugin.registerFunction(name: string, fn: Function, options?: NvimFunctionOptions): void;
  NvimPlugin.registerFunction(name: string, fn: [any, Function], options?: NvimFunctionOptions): void;

  interface NvimFunctionOptions {
    sync?: boolean;
    range?: string;
    eval?: string;

Registers a function with name name, calling function fn with options. This will be invoked from nvim by entering eg :call name() in normal mode.


Examples of how to write plugins can be seen in the examples directory.

Debugging / troubleshooting

Here are a few env vars you can set while starting neovim, that can help debugging and configuring logging:


Will spawn the node process that calls neovim-client-host with --inspect-brk so you can have a debugger. Pair that with this Node Inspector Manager Chrome plugin


Logging is done using winston through the logger module. Plugins have console replaced with this interface.


Sets the logging level for winston. Default is debug, available levels are { error: 0, warn: 1, info: 2, verbose: 3, debug: 4, silly: 5 }


Sets the log file path

Usage through node REPL


First, start Nvim with a known address (or use the $NVIM_LISTEN_ADDRESS of a running instance):

$ NVIM_LISTEN_ADDRESS=/tmp/nvim nvim In another terminal, connect a node REPL to Nvim

// `scripts/nvim` will detect if `NVIM_LISTEN_ADDRESS` is set and use that unix socket
// Otherwise will create an embedded `nvim` instance
require('neovim/scripts/nvim').then((nvim) => {

The tests and scripts can be consulted for more examples.