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Mar 25, 2022
Jul 12, 2022

VSCode Language Server - Node

This repository contains the code for the following npm modules:

  • vscode-languageclient: npm module to talk to a VSCode language server from a VSCode extension:
    NPM Version NPM Downloads
  • vscode-languageserver: npm module to implement a VSCode language server using Node.js as a runtime:
    NPM Version NPM Downloads
  • vscode-languageserver-textdocument: npm module to implement text documents usable in a LSP server using Node.js as a runtime:
    NPM Version NPM Downloads
  • vscode-languageserver-protocol: the actual language server protocol definition in TypeScript:
    NPM Version NPM Downloads
  • vscode-languageserver-types: data types used by the language server client and server:
    NPM Version NPM Downloads
  • vscode-jsonrpc: the underlying message protocol to communicate between a client and a server:
    NPM Version NPM Downloads

All four npm modules are built using one travis build. Its status is:

Build Status

Click here for a detailed document on how to use these npm modules to implement language servers for VSCode.


After cloning the repository, run npm install to install dependencies and npm run symlink to point packages in this repository to each other.


3.17.2 Protocol, 8.0.2 JSON-RPC, 8.0.2 Client and 8.0.2 Server.

  • make client more robust against unwanted restarts
  • added a LanguageClient#dispose method to fully dispose a client
  • various bug fixes.

3.17.0 Protocol, 8.0.0 JSON-RPC, 8.0.0 Client and 8.0.0 Server.

Library specific changes are:

  • cleanup of client start and stop methods. Both methods now return a promise since these methods are async. This is a breaking change since start returned a disposable before. Extensions should now implement a deactivate function in their extension main file and correctly return the stop promise from the deactivate call. As a consequence the onReady() got removed since extensions can await the start() call now. Old code like this
const client: LanguageClient = ...;
await client.onReady();

should become:

const client: LanguageClient = ...;
await client.start();
  • notification and request handler registration can now happen before the client is started. This ensures that no messages from the server are missed.
  • if an extension sends a notification or request before the client got started the client will auto start.
  • all sendNotification methods now return a promise. Returning a promise was necessary since the actual writing of the message to the underlying transport is async and a client for example could not determine if a notification was handed off to the transport. This is a breaking change in the sense that it might result in floating promise and might be flagged by a linter.
  • all handler registrations now return a Disposable to allow unregistration of the handler.
  • the behavior of handleFailedRequest has change. Instead of returning a default value when a exception is received from the server the method now rethrows the error. This ensures that VS Code's default behavior on errors is used. The method also handles the RequestCancelled and ServerCancelled in the following way:
    • if it receives ServerCancelled and the client didn't cancel the request as well throw CancellationError to ask the client to rerun the request.
    • if it receives RequestCancelled then normally the client should have cancelled the request and the code will return the default value (according to the best interpretation of the 3.16 spec). If the client has not canceled interpret the RequestCancelled as ServerCancelled.
  • the next handler of a client middleware now drops server results if the request got already canceled on the client side by returning VS Code's default value for the corresponding provider (mostly null). This is a breaking change since in former releases of the library the middleware would see the result also not used by VS Code. The change was made to save CPU and memory by not converting unused response results.
  • all converter functions which take an array are now async, yield and take a cancellation token. This is a breaking change and got introduced to avoid monopolizing the extension host during type conversions.
  • the return type of ErrorHandler#error and ErrorHandler#closed changed in a breaking manner. It now supports return an optional message which will be displayed to the user.
  • Added support for inline values.
  • Added support for inlay hints.
  • Added support for type hierarchies.
  • Added support for notebook documents.

3.16.0 Protocol, 6.0.0 JSON-RPC, 7.0.0 Client and 7.0.0 Server.

For a detailed list of changes made in the 3.16.0 version of the protocol see the change log of the 3.16 specification.

Library specific changes are:

  • cleanup of Request and Notification types. Removed the unnecessary generic parameter RO. This is a breaking change. To adapt simply remove the type argument.
  • added the new concept of a RegistrationType which decouple the registration method from the actual request or notification method. This is a breaking change for implementors of custom features. To adapt rename the messages property to registrationType and return a corresponding RegistrationType. Additional remove the first parameter from the register method.
  • cleanup of ErrorCodes. LSP specific error codes got moved to a new namespace LSPErrorCodes. The namespace ErrorCodes in jsonrpc is not correctly reserved for JSON RPC specific error codes. This is a breaking change. To resolve it use LSPErrorCodes instead.
  • split code into common, node and browser to allow using the LSP client and server npm modules in a Web browser via webpack. This is a breaking change and might lead to compile / runtime errors if not adopted. Every module has now three different exports which represent the split into common, node and browser. Lets look at vscode-jsonrpc for an example: (a) the import vscode-jsonrpc will only import the common code, (b) the import vscode-jsonrpc\node will import the common and the node code and (c) the import vscode-jsonrpc\browser will import the common and browser code.
  • added support to control the parameter structure when sending requests and notifications in vscode-jsonrpc. The parameter structure can be controlled using the additional parameterStructures argument when creating a request or notification type or when sending an untyped request or notification using the sendRequest or sendNotification function. The default is which does the following:
    • use byPosition for messages with zero or greater than one parameter
    • for one parameter it used byName for parameters which are object literals. Uses byPosition for all other parameters.

3.15.3 Protocol, 6.1.x client and 6.1.x server

  • Small changes to the proposed support for semantic tokens.

3.15.2 Protocol, 6.1.x client and 6.1.x server

  • Proposed support for semantic tokens.

3.15.0 Protocol, 6.0.0 Client & 6.0.0 Server

  • Progress support for work done and partial result progress.
  • Proposed implementation for call hierarchies.
  • SelectionRangeRequest protocol added:
    • New APIs in Types: SelectionRange
    • New APIs in Protocol: SelectionRangeRequest, SelectionRangeParams, SelectionRangeClientCapabilities, SelectionRangeServerCapabilities, SelectionRangeProviderOptions,
  • Support for custom text document implementations:
    • new npm package vscode-languageserver-textdocument which ships a standard text document implementation with basic incremental update. Server now need to pre-requisite this npm package.
    • deprecated text document implementation in types.
    • this resulted in a small breakage on the server side. Instead of doing new TextDocuments you now have to pass in a text document configuration to provide callbacks to create and update a text document. Here are examples in TypeScript and JavaScript
import { TextDocuments } from 'vscode-languageserver';
import { TextDocument } from 'vscode-languageserver-textdocument';
const documents = new TextDocuments(TextDocument);
const server = require("vscode-languageserver");
const textDocument = require("vscode-languageserver-textdocument");
const documents = new server.TextDocuments(textDocument.TextDocument);

5.1.1 Client

5.1.0 Client & 5.1.0 Server

  • Adopt protocol version 3.13.0

3.13.0 Protocol

  • FoldingRangeRequestParam renamed to 'FoldingRangeParams' (FoldingRangeRequestParam still provided for backward compatibility)
  • Added support for create, rename and delete file operations in workspace edits.

5.0.0 Client & 5.0.0 Server

  • Make the client work with Electron 2.x. which is used since VS Code 1.26.x
  • Check that the expected client version specified in engines.vscode in the package.json file matches the VS Code version the client is running on.

4.4.0 Client & 4.4.0 Server & 3.10.0 Protocol

  • Implement hierarchical document outline
  • Color, ColorInformation, ColorPresentation moved to Types
  • FoldingRangeRequest protocol added:
    • New APIs in Types: FoldingRange, FoldingRangeKind
    • New APIs in Protocol: FoldingRangeRequest, FoldingRangeRequestParam, FoldingRangeClientCapabilities, FoldingRangeServerCapabilities, FoldingRangeProviderOptions,

4.3.0 Client & 4.3.0 Server & 3.9.0 Protocol

  • Add support for preselect property on CompletionItem

4.2.0 Client & 4.2.0 Server & 3.8.0 Protocol

4.1.4 Client & 4.1.3 Server

4.1.1 Client

4.1.0 Client & Server

4.0.1 Client

  • removed unnecessary console log statement.

4.0.0 Server and Client

  • implemented the latest protocol additions. Noteworthy are completion context, extensible completion item and symbol kind as well as markdown support for completion item and signature help. Moved to 4.0.0 version since the introduction of the completion context required a breaking change in the client middleware. The old signature:
provideCompletionItem?: (this: void, document: TextDocument, position: VPosition, token: CancellationToken, next: ProvideCompletionItemsSignature) => ProviderResult<VCompletionItem[] | VCompletionList>;

contains now an additional argument context:

provideCompletionItem?: (this: void, document: TextDocument, position: VPosition, context: VCompletionContext, token: CancellationToken, next: ProvideCompletionItemsSignature) => ProviderResult<VCompletionItem[] | VCompletionList>;

6.0.0 Server and Client

  • Move to Protocol 3.15.0
  • move JS target to ES2017

3.15.0 Types and Protocol

  • Implement LSP 3.15.0

3.6.1 Types

  • ESM added as output format (for Webpack and other ESM consumers)

3.5.0 Server and Client

  • allow the client to start the server in detached mode. If the server is running detached the client will not monitor the server process and kill it on shutdown.
  • bug fixing.

3.4.0 Server and Client

  • a new npm module vscode-languageserver-protocol has been added which contains the protocol definitions in TypeScript. This module is now shared between the client and the server.
  • support for proposed protocol has been added to the protocol, client and server npm modules. Proposed protocol is subject to change even if it ships in a stable version of the npm modules.
  • proposed protocol has been added for the following features:
    • configuration: support to fetch configuration settings by sending a request from the server to the client
    • workspaceFolders: support to handle more than one root folder per workspace
    • colorProvider: support to compute color ranges for a document

3.3.0 Server and Client

  • splitted the client into a base client and a main client to support reusing the client implementation in other environments.
  • made the request processing more async. So instead of processing a request immediately when the code gets notified by a Node.js callback the request is now put into a queue and processed from the queue. This allows for better dropping or folding of events if necessary.
  • bugs fixes see April and May

3.2.1 Server and Client

3.2.0 Server and Client

3.1.0 Server and Client

  • add support for named pipes and socket file transport
  • fixed dead lock problem with node-ipc.

3.0.5 Server and 3.0.4 Client

  • deprecated Files.uriToFilePath in favour of the vscode-uri npm module which provides a more complete implementation of URI for VS Code.
  • made rootPath optional since it is deprecated in 3.x.

3.0.3: Client, Server and JSON-RPC

New Features

  • Moved all libraries to TypeScript 2.x.x
  • Client and Server are compiled to ES6. JSON-RPC is still compiled to ES5.
  • JSON-RPC supports n parameter request and notification invocation.
  • Support for the 3.0 version of the Language Server protocol. Some highlights are:
    • Support for feature flags.
    • Support for dynamic registration. In the 2.x version of the library a server announced its capabilities statically. In 3.x the server can now dynamically register and un-register capability handlers using the new requests client/registerCapability and client/unregisterCapability.
    • Support to delegate command execution via a new request workspace/executeCommand to the server.
  • Support for snippets in completion items:
    • New type InsertTextFormat
    • CompletionItem.insertTextFormat controls whether the inserted test is interpreted as a plain text or a snippet.

Breaking changes:

  • to ensure ordered delivery of notifications and requests the language client now throws if sendRequest, onRequest, sendNotification or onNotification is called before the client is ready. Use the onReady() Promise to wait until the client is ready.
let client = new LanguageClient(...);
client.onReady().then(() => {
  • removed the deprecated module functions on code2Protocol and protocol2Code converters. Use the corresponding properties on the LanguageClient instance instead to get access to the same converters used by the LanguageClient.
// Old
import { Protocol2Code, ... } from 'vscode-languageclient';
// New
let client = new LanguageClient(...);
  • due to the use of TypeScript 2.x.x and differences in d.ts generation users of the new version need to move to TypeScript 2.x.x as well. Usually the LanguageClient is used in a VS Code extension. You can find detailed steps on how to upgrade a VS Code extension to TypeScript 2.x.x here.
  • activeSignature and activeParameter where incorrectly declared as optional in SignatureHelp. They are now mandatory.
  • the protocol.ts file used enum types in 2.x. However the protocol itself is number based since no assumption can be made about the presence of an enum type in the implementing language. To make this more clear the enum got replace by number types with a or literal type definition. This might result in compile errors if a number was directly assigned to a previous enum type without a proper range check.
  • Request and Notification types are now classes instead of interfaces. In addition they now take an additional type argument to type the registration options for dynamic registration. Adopting to that change is quite easy. Simply new the RequestType or NotificationType and add void as the registration option type. Please remember to update this on both the client and server side:
// Old
export namespace MyRequest {
  export const type: RequestType<MyParams, MyResult, void> = { get method() { return 'myRequest'; } };
export namespace MyNotification {
  export const type: NotificationType<MyParams> = { get method() { return 'myNotification'; } };
// New
export namespace MyRequest {
  export const type = new RequestType<MyParams, MyResult, void, void>('myRequest');
export namespace MyNotification {
  export const type = new NotificationType<MyParams, void>('myNotification');

2.6.0: Client and server

  • Support for Document Link Providers
  • Support for additional text edits and commands in completion items.

2.5.0: Client and Server

  • Better error handling on client side.
  • Events for starting and stopping the server.
  • Initialization options can be provided as a function.
  • Support for stdio / stderr encoding.
  • Support to convert URIs between the client and the server.
  • Server connection.console logging now appears in the corresponding output channel instead of in the developer console.
  • If a non stdio communication channel is used between client and server the server's stdio is redirected to the output channel.
  • A client can now have an id and a name.

2.4.0 Client and Server

  • Data types such as Range, Position, TextDocument, Hover, CompletionItem... extracted to new node module vscode-languageserver-types. The new node module is shared between the server and client and can also be used by language service libraries that want to use the same data types.

2.3.0: Client only

  • the client now restarts the server if the server crashes without a prior exit notification sent. The strategy used to restart the server is plugable (see LanguageClientOptions.errorHandler). The default strategy restart the server unless it crashed 5 times or more in the last 3 minutes.

2.0: A detailed description of the 2.0 version can be found here. A summary of the changes:

  • support for request cancellation. Cancellation is automatically hooked to VSCode's cancellation tokens
  • document save notification.
  • Synced text documents carry VSCode's text document version number

1.1.x: Provides all language service feature available in the extension host via the language client / server protocol. Features added:

  • Code Actions: provide actions to fix diagnostic problems.
  • Code Lens: provide commands that are shown along with source text.
  • Formatting: whole document, document ranges and formatting on type.
  • Rename refactoring: provides renaming symbols.

1.0.x: Version which provides support for the following features:

  • Transports: stdio and node IPC can be used as a transport.
  • Document synchronization: incremental and full text document synchronization.
  • Configuration synchronization: synchronization of configuration settings to the server.
  • File events: synchronization of file events to the server.
  • Code Complete: provides code complete lists.
  • Document Highlights: highlights all 'equal' symbols in a text document.
  • Hover: provides hover information for a symbol selected in a text document.
  • Signature Help: provides signature help for a symbol selected in a text document.
  • Goto Definition: provides goto definition support for a symbol selected in a text document.
  • Find References: finds all project-wide references for a symbol selected in a text document.
  • List Document Symbols: lists all symbols defined in a text document.
  • List Workspace Symbols: lists all project-wide symbols.

0.10.x: Initial versions to build a good API for the client and server side




Language server protocol implementation for VSCode. This allows implementing language services in JS/TS running on node.js



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