# VSCode JSON Language Server [![NPM Version](https://img.shields.io/npm/v/vscode-json-languageserver.svg)](https://npmjs.org/package/vscode-json-languageserver) [![NPM Downloads](https://img.shields.io/npm/dm/vscode-json-languageserver.svg)](https://npmjs.org/package/vscode-json-languageserver) [![NPM Version](https://img.shields.io/npm/l/vscode-json-languageserver.svg)](https://npmjs.org/package/vscode-json-languageserver) The JSON Language server provides language-specific smarts for editing, validating and understanding JSON documents. It runs as a separate executable and implements the [language server protocol](https://microsoft.github.io/language-server-protocol/overview) to be connected by any code editor or IDE. ## Capabilities ### Server capabilities The JSON language server supports requests on documents of language id `json` and `jsonc`. - `json` documents are parsed and validated following the [JSON specification](https://tools.ietf.org/html/rfc7159). - `jsonc` documents additionally accept single line (`//`) and multi-line comments (`/* ... */`). JSONC is a VSCode specific file format, intended for VSCode configuration files, without any aspirations to define a new common file format. The server implements the following capabilities of the language server protocol: - [Code completion](https://microsoft.github.io/language-server-protocol/specification#textDocument_completion) for JSON properties and values based on the document's [JSON schema](http://json-schema.org/) or based on existing properties and values used at other places in the document. JSON schemas are configured through the server configuration options. - [Hover](https://microsoft.github.io/language-server-protocol/specification#textDocument_hover) for values based on descriptions in the document's [JSON schema](http://json-schema.org/). - [Document Symbols](https://microsoft.github.io/language-server-protocol/specification#textDocument_documentSymbol) for quick navigation to properties in the document. - [Document Colors](https://microsoft.github.io/language-server-protocol/specification#textDocument_documentColor) for showing color decorators on values representing colors and [Color Presentation](https://microsoft.github.io/language-server-protocol/specification#textDocument_colorPresentation) for color presentation information to support color pickers. The location of colors is defined by the document's [JSON schema](http://json-schema.org/). All values marked with `"format": "color-hex"` (VSCode specific, non-standard JSON Schema extension) are considered color values. The supported color formats are `#rgb[a]` and `#rrggbb[aa]`. - [Code Formatting](https://microsoft.github.io/language-server-protocol/specification#textDocument_rangeFormatting) supporting ranges and formatting the whole document. - [Folding Ranges](https://microsoft.github.io/language-server-protocol/specification#textDocument_foldingRange) for all folding ranges in the document. - Semantic Selection for semantic selection for one or multiple cursor positions. - [Goto Definition](https://microsoft.github.io/language-server-protocol/specification#textDocument_definition) for $ref references in JSON schemas - [Diagnostics (Validation)](https://microsoft.github.io/language-server-protocol/specification#textDocument_publishDiagnostics) are pushed for all open documents - syntax errors - structural validation based on the document's [JSON schema](http://json-schema.org/). In order to load JSON schemas, the JSON server uses NodeJS `http` and `fs` modules. For all other features, the JSON server only relies on the documents and settings provided by the client through the LSP. ### Client requirements: The JSON language server expects the client to only send requests and notifications for documents of language id `json` and `jsonc`. The JSON language server has the following dependencies on the client's capabilities: - Code completion requires that the client capability has *snippetSupport*. If not supported by the client, the server will not offer the completion capability. - Formatting support requires the client to support *dynamicRegistration* for *rangeFormatting*. If not supported by the client, the server will not offer the format capability. ## Configuration ### Initialization options The client can send the following initialization options to the server: - `provideFormatter: boolean | undefined`. If defined, the value defines whether the server provides the `documentRangeFormattingProvider` capability on initialization. If undefined, the setting `json.format.enable` is used to determine whether formatting is provided. The formatter will then be registered through dynamic registration. If the client does not support dynamic registration, no formatter will be available. - `handledSchemaProtocols`: The URI schemas handles by the server. See section `Schema configuration` below. - `customCapabilities`: Additional non-LSP client capabilities: - `rangeFormatting: { editLimit: x } }`: For performance reasons, limit the number of edits returned by the range formatter to `x`. ### Settings Clients may send a `workspace/didChangeConfiguration` notification to notify the server of settings changes. The server supports the following settings: - http - `proxy`: The URL of the proxy server to use when fetching schema. When undefined or empty, no proxy is used. - `proxyStrictSSL`: Whether the proxy server certificate should be verified against the list of supplied CAs. - json - `format` - `enable`: Whether the server should register the formatting support. This option is only applicable if the client supports *dynamicRegistration* for *rangeFormatting* and `initializationOptions.provideFormatter` is not defined. - `schemas`: Configures association of file names to schema URL or schemas and/or associations of schema URL to schema content. - `fileMatch`: an array of file names or paths (separated by `/`). `*` can be used as a wildcard. Exclusion patterns can also be defined and start with '!'. A file matches when there is at least one matching pattern and the last matching pattern is not an exclusion pattern. - `url`: The URL of the schema, optional when also a schema is provided. - `schema`: The schema content. - `resultLimit`: The max number folding ranges and outline symbols to be computed (for performance reasons) ```json { "http": { "proxy": "", "proxyStrictSSL": true }, "json": { "format": { "enable": true }, "schemas": [ { "fileMatch": [ "foo.json", "*.superfoo.json" ], "url": "http://json.schemastore.org/foo", "schema": { "type": "array" } } ] } } ``` ### Schema configuration and custom schema content delivery [JSON schemas](http://json-schema.org/) are essential for code assist, hovers, color decorators to work and are required for structural validation. To find the schema for a given JSON document, the server uses the following mechanisms: - JSON documents can define the schema URL using a `$schema` property - The settings define a schema association based on the documents URL. Settings can either associate a schema URL to a file or path pattern, and they can directly provide a schema. - Additionally, schema associations can also be provided by a custom 'schemaAssociations' configuration call. Schemas are identified by URLs. To load the content of a schema, the JSON language server either tries to load from that URI or path itself or delegates to the client. The `initializationOptions.handledSchemaProtocols` initialization option defines which URLs are handled by the server. Requests for all other URIs are sent to the client. `handledSchemaProtocols` is part of the initialization options and can't be changed while the server is running. ```ts let clientOptions: LanguageClientOptions = { initializationOptions: { handledSchemaProtocols: ['file'] // language server should only try to load file URLs } ... } ``` If `handledSchemaProtocols` is not set, the JSON language server will load the following URLs itself: - `http`, `https`: Loaded using NodeJS's HTTP support. Proxies can be configured through the settings. - `file`: Loaded using NodeJS's `fs` support. #### Schema content request Requests for schemas with URLs not handled by the server are forwarded to the client through an LSP request. This request is a JSON language server-specific, non-standardized, extension to the LSP. Request: - method: 'vscode/content' - params: `string` - The schema URL to request. - response: `string` - The content of the schema with the given URL #### Schema content change notification When the client is aware that a schema content has changed, it will notify the server through a notification. This notification is a JSON language server-specific, non-standardized, extension to the LSP. The server will, as a response, clear the schema content from the cache and reload the schema content when required again. #### Schema associations notification In addition to the settings, schemas associations can also be provided through a notification from the client to the server. This notification is a JSON language server-specific, non-standardized, extension to the LSP. Notification: - method: 'json/schemaAssociations' - params: `ISchemaAssociations` or `ISchemaAssociation[]` defined as follows ```ts interface ISchemaAssociations { /** * An object where: * - keys are file names or file paths (using `/` as path separator). `*` can be used as a wildcard. * - values are an arrays of schema URIs */ [pattern: string]: string[]; } interface ISchemaAssociation { /** * The URI of the schema, which is also the identifier of the schema. */ uri: string; /** * A list of file path patterns that are associated to the schema. The '*' wildcard can be used. Exclusion patterns starting with '!'. * For example '*.schema.json', 'package.json', '!foo*.schema.json'. * A match succeeds when there is at least one pattern matching and last matching pattern does not start with '!'. */ fileMatch: string[]; /* * The schema for the given URI. * If no schema is provided, the schema will be fetched with the schema request service (if available). */ schema?: JSONSchema; } ``` `ISchemaAssociations` - keys: a file names or file path (separated by `/`). `*` can be used as a wildcard. - values: An array of schema URLs Notification: - method: 'json/schemaContent' - params: `string` the URL of the schema that has changed. ### Item Limit If the setting `resultLimit` is set, the JSON language server will limit the number of folding ranges and document symbols computed. When the limit is reached, a notification `json/resultLimitReached` is sent that can be shown that can be shown to the user. Notification: - method: 'json/resultLimitReached' - params: a human readable string to show to the user. ## Try The JSON language server is shipped with [Visual Studio Code](https://code.visualstudio.com/) as part of the built-in VSCode extension `json-language-features`. The server is started when the first JSON file is opened. The [VSCode JSON documentation](https://code.visualstudio.com/docs/languages/json) for detailed information on the user experience and has more information on how to configure the language support. ## Integrate If you plan to integrate the JSON language server into an editor and IDE, check out [this page](https://microsoft.github.io/language-server-protocol/implementors/tools/) if there's already an LSP client integration available. You can also launch the language server as a command and connect to it. For that, install the `json-language-server` npm module: `npm install -g json-language-server` Start the language server with the `json-language-server` command. Use a command line argument to specify the preferred communication channel: ``` json-language-server --node-ipc json-language-server --stdio json-language-server --socket=<port> ``` To connect to the server from NodeJS, see Remy Suen's great write-up on [how to communicate with the server](https://github.com/rcjsuen/dockerfile-language-server-nodejs#communicating-with-the-server) through the available communication channels. ## Participate The source code of the JSON language server can be found in the [VSCode repository](https://github.com/microsoft/vscode) at [extensions/json-language-features/server](https://github.com/microsoft/vscode/tree/master/extensions/json-language-features/server). File issues and pull requests in the [VSCode GitHub Issues](https://github.com/microsoft/vscode/issues). See the document [How to Contribute](https://github.com/microsoft/vscode/wiki/How-to-Contribute) on how to build and run from source. Most of the functionality of the server is located in libraries: - [jsonc-parser](https://github.com/microsoft/node-jsonc-parser) contains the JSON parser and scanner. - [vscode-json-languageservice](https://github.com/microsoft/vscode-json-languageservice) contains the implementation of all features as a re-usable library. - [vscode-languageserver-node](https://github.com/microsoft/vscode-languageserver-node) contains the implementation of language server for NodeJS. Help on any of these projects is very welcome. ## Code of Conduct This project has adopted the [Microsoft Open Source Code of Conduct](https://opensource.microsoft.com/codeofconduct/). For more information see the [Code of Conduct FAQ](https://opensource.microsoft.com/codeofconduct/faq/) or contact [opencode@microsoft.com](mailto:opencode@microsoft.com) with any additional questions or comments. ## License Copyright (c) Microsoft Corporation. All rights reserved. Licensed under the [MIT](https://github.com/microsoft/vscode/blob/master/LICENSE.txt) License.