Common Extension Points#

Most of the component parts of JupyterLab are designed to be extensible, and they provide services that can be requested in extensions via tokens. A list of common core tokens that extension authors can request is given in Core Plugins.

Following the list of core tokens is a guide for using some of JupyterLab’s most commonly-used extension points. However, it is not an exhaustive account of how to extend the application components, and more detailed descriptions of their public APIs may be found in the JupyterLab and Lumino API documentation.

Core Plugins #

The core packages of JupyterLab provide the following plugins. They can be enabled or disabled using the command jupyter labextension enable <plugin-id> or jupyter labextension disable <plugin-id>.

@jupyterlab/javascript-extension:factory: Adds renderer for JavaScript content.
@jupyterlab/json-extension:factory: Adds renderer for JSON content.
@jupyterlab/json-lines-extension:factory: Adds renderer for JSONLines content.
@jupyterlab/mermaid-extension:factory: Provides a renderer for mermaid text-based diagrams.
@jupyterlab/pdf-extension:factory: Adds renderer for PDF content.
@jupyterlab/vega5-extension:factory: Provides a renderer for Vega 5 and Vega-Lite 3 to 5 content.
@jupyterlab/application:mimedocument: Provides a mime document widget tracker.
@jupyterlab/application-extension:context-menu: Populates the context menu.
@jupyterlab/application-extension:dirty: Adds safeguard dialog when closing the browser tab with unsaved modifications.
@jupyterlab/application-extension:main: Initializes the application and provides the URL tree path handler.
@jupyterlab/application-extension:commands: Adds commands related to the shell.
@jupyterlab/application-extension:layout: Provides the shell layout restorer.
@jupyterlab/application-extension:router: Provides the URL router
@jupyterlab/application-extension:tree-resolver: Provides the tree route resolver
@jupyterlab/application-extension:notfound: Defines the behavior for not found URL (aka route).
@jupyterlab/application-extension:faviconbusy: Handles the favicon depending on the application status.
@jupyterlab/application-extension:shell: Provides the JupyterLab shell. It has an extended API compared to app.shell.
@jupyterlab/application-extension:status: Provides the application status.
@jupyterlab/application-extension:info: Provides the application information.
@jupyterlab/application-extension:mode-switch: Adds the interface mode switch
@jupyterlab/application-extension:paths: Provides the application paths.
@jupyterlab/application-extension:property-inspector: Provides the property inspector.
@jupyterlab/application-extension:logo: Sets the application logo.
@jupyterlab/application-extension:top-bar: Adds a toolbar to the top area (next to the main menu bar).
@jupyterlab/apputils-extension:announcements: Add the announcement feature. It will fetch news on the internet and check for application updates.
@jupyterlab/apputils-extension:kernel-status: Provides the kernel status indicator model.
@jupyterlab/apputils-extension:notification: Add the notification center and its status indicator.
@jupyterlab/apputils-extension:palette: Provides the command palette.
@jupyterlab/apputils-extension:palette-restorer: Restores the command palette.
@jupyterlab/apputils-extension:print: Add the print capability
@jupyterlab/apputils-extension:resolver: Provides the window name resolver.
@jupyterlab/apputils-extension:running-sessions-status: Add the running sessions and terminals status bar item.
@jupyterlab/apputils-extension:sanitizer: Provides the HTML sanitizer.
@jupyterlab/apputils-extension:settings: Provides the setting registry.
@jupyterlab/apputils-extension:state: Provides the application state. It is stored per workspaces.
@jupyterlab/apputils-extension:splash: Provides the splash screen.
@jupyterlab/apputils-extension:sessionDialogs: Provides the session context dialogs.
@jupyterlab/apputils-extension:themes: Provides the theme manager.
@jupyterlab/apputils-extension:themes-palette-menu: Adds theme commands to the menu and the command palette.
@jupyterlab/apputils-extension:toggle-header: Adds a command to display the main area widget content header.
@jupyterlab/apputils-extension:toolbar-registry: Provides toolbar items registry.
@jupyterlab/apputils-extension:utilityCommands: Adds meta commands to run set of other commands.
@jupyterlab/apputils-extension:workspaces: Add workspace file type and commands.
@jupyterlab/cell-toolbar-extension:plugin: Add the cells toolbar.
@jupyterlab/celltags-extension:plugin: Adds the cell tags editor.
@jupyterlab/codemirror-extension:languages: Provides the CodeMirror languages registry.
@jupyterlab/codemirror-extension:themes: Provides the CodeMirror theme registry
@jupyterlab/codemirror-extension:binding: Register the CodeMirror extension factory binding the editor and the shared model.
@jupyterlab/codemirror-extension:extensions: Provides the CodeMirror extension factory registry.
@jupyterlab/codemirror-extension:services: Provides the service to instantiate CodeMirror editors.
@jupyterlab/codemirror-extension:line-col-status: Provides the code editor cursor position model.
@jupyterlab/completer-extension:manager: Provides the completion provider manager.
@jupyterlab/completer-extension:base-service: Adds context and kernel completion providers.
@jupyterlab/completer-extension:inline-history: Adds inline completion provider suggesting code from execution history.
@jupyterlab/completer-extension:inline-completer-factory: Provides a factory for inline completer.
@jupyterlab/completer-extension:inline-completer: Provides a factory for inline completer.
@jupyterlab/console-extension:factory: Provides the console widget content factory.
@jupyterlab/console-extension:tracker: Provides the console widget tracker.
@jupyterlab/console-extension:foreign: Add foreign handler of IOPub messages to the console.
@jupyterlab/console-extension:kernel-status: Adds the console to the kernel status indicator model.
@jupyterlab/console-extension:cursor-position: Adds the console to the code editor cursor position model.
@jupyterlab/console-extension:completer: Adds completion to the console.
@jupyterlab/csvviewer-extension:csv: Adds viewer for CSV file types
@jupyterlab/csvviewer-extension:tsv: Adds viewer for TSV file types.
@jupyterlab/debugger-extension:service: Provides the debugger service.
@jupyterlab/debugger-extension:consoles: Add debugger capability to the consoles.
@jupyterlab/debugger-extension:files: Adds debugger capabilities to files.
@jupyterlab/debugger-extension:notebooks: Adds debugger capability to notebooks and provides the debugger notebook handler.
@jupyterlab/debugger-extension:variables: Adds variables renderer and inspection in the debugger variable panel.
@jupyterlab/debugger-extension:sidebar: Provides the debugger sidebar.
@jupyterlab/debugger-extension:main: Initialize the debugger user interface.
@jupyterlab/debugger-extension:sources: Provides the source feature for debugging
@jupyterlab/debugger-extension:source-viewer: Initialize the debugger sources viewer.
@jupyterlab/debugger-extension:config: Provides the debugger configuration
@jupyterlab/docmanager-extension:manager: Provides the document manager.
@jupyterlab/docmanager-extension:plugin: Adds commands and settings to the document manager.
@jupyterlab/docmanager-extension:contexts: Adds the handling of opened documents dirty state.
@jupyterlab/docmanager-extension:path-status: Adds a file path indicator in the status bar.
@jupyterlab/docmanager-extension:saving-status: Adds a saving status indicator.
@jupyterlab/docmanager-extension:download: Adds command to download files.
@jupyterlab/docmanager-extension:open-browser-tab: Adds command to open a browser tab.
@jupyterlab/docmanager-extension:opener: Provides the widget opener.
@jupyterlab/documentsearch-extension:plugin: Provides the document search registry.
@jupyterlab/documentsearch-extension:labShellWidgetListener: Active search on valid document
@jupyterlab/extensionmanager-extension:plugin: Adds the extension manager plugin.
@jupyterlab/filebrowser-extension:factory: Provides the file browser factory.
@jupyterlab/filebrowser-extension:default-file-browser: Provides the default file browser
@jupyterlab/filebrowser-extension:browser: Set up the default file browser (commands, settings,…).
@jupyterlab/filebrowser-extension:share-file: Adds the “Copy Shareable Link” command; useful for JupyterHub deployment for example.
@jupyterlab/filebrowser-extension:file-upload-status: Adds a file upload status widget.
@jupyterlab/filebrowser-extension:download: Adds the download file commands. Disabling this plugin will NOT disable downloading files from the server, if the user enters the appropriate download URLs.
@jupyterlab/filebrowser-extension:widget: Adds the file browser to the application shell.
@jupyterlab/filebrowser-extension:open-with: Adds the open-with feature allowing an user to pick the non-preferred document viewer.
@jupyterlab/filebrowser-extension:open-browser-tab: Adds the open-in-new-browser-tab features.
@jupyterlab/filebrowser-extension:open-url: Adds the feature “Open files from remote URLs”.
@jupyterlab/fileeditor-extension:plugin: Provides the file editor widget tracker.
@jupyterlab/fileeditor-extension:cursor-position: Adds a file editor cursor position status widget.
@jupyterlab/fileeditor-extension:completer: Adds the completer capability to the file editor.
@jupyterlab/fileeditor-extension:language-server: Adds Language Server capability to the file editor.
@jupyterlab/fileeditor-extension:search: Adds search capability to the file editor.
@jupyterlab/fileeditor-extension:editor-syntax-status: Adds a file editor syntax status widget.
@jupyterlab/fileeditor-extension:tab-space-status: Adds a file editor indentation status widget.
@jupyterlab/help-extension:about: Adds a “About” dialog feature.
@jupyterlab/help-extension:jupyter-forum: Adds command to open the Jupyter Forum website.
@jupyterlab/help-extension:open: Add command to open websites as panel or browser tab.
@jupyterlab/help-extension:resources: Adds menu entries to Jupyter reference documentation websites.
@jupyterlab/help-extension:licenses: Adds licenses used report tools.
@jupyterlab/htmlviewer-extension:plugin: Adds HTML file viewer and provides its tracker.
@jupyterlab/hub-extension:plugin: Registers commands related to the hub server
@jupyterlab/hub-extension:menu: Adds hub related commands to the menu.
@jupyterlab/hub-extension:connectionlost: Provides a service to be notified when the connection to the hub server is lost.
@jupyterlab/imageviewer-extension:plugin: Adds image viewer and provide its tracker.
@jupyterlab/inspector-extension:inspector: Provides the code introspection widget.
@jupyterlab/inspector-extension:consoles: Adds code introspection support to consoles.
@jupyterlab/inspector-extension:notebooks: Adds code introspection to notebooks.
@jupyterlab/launcher-extension:plugin: Provides the launcher tab service.
@jupyterlab/logconsole-extension:plugin: Provides the logger registry.
@jupyterlab/lsp-extension:plugin: Provides the language server connection manager.
@jupyterlab/lsp-extension:feature: Provides the language server feature manager.
@jupyterlab/lsp-extension:settings: Provides the language server settings.
@jupyterlab/lsp:ILSPCodeExtractorsManager: Provides the code extractor manager.
@jupyterlab/lsp-extension:tracker: Provides the tracker of WidgetLSPAdapter.
@jupyterlab/mainmenu-extension:plugin: Adds and provides the application main menu.
@jupyterlab/markdownviewer-extension:plugin: Adds markdown file viewer and provides its tracker.
@jupyterlab/markedparser-extension:plugin: Provides the Markdown parser.
@jupyterlab/mathjax-extension:plugin: Provides the LaTeX mathematical expression interpreter.
@jupyterlab/mermaid-extension:core: Provides the Mermaid manager.
@jupyterlab/mermaid-extension:markdown: Provides the Mermaid markdown renderer.
@jupyterlab/mermaid-extension:context-commands: Provides context menu commands for mermaid diagrams.
@jupyterlab/metadataform-extension:metadataforms: Provides the metadata form registry.
@jupyterlab/notebook-extension:factory: Provides the notebook cell factory.
@jupyterlab/notebook-extension:tracker: Provides the notebook widget tracker.
@jupyterlab/notebook-extension:execution-indicator: Adds a notebook execution status widget.
@jupyterlab/notebook-extension:export: Adds the export notebook commands.
@jupyterlab/notebook-extension:tools: Provides the notebook tools.
@jupyterlab/notebook-extension:mode-status: Adds a notebook mode status widget.
@jupyterlab/notebook-extension:trust-status: Adds the notebook trusted status widget.
@jupyterlab/notebook-extension:widget-factory: Provides the notebook widget factory.
@jupyterlab/notebook-extension:log-output: Adds cell outputs log to the application logger.
@jupyterlab/notebook-extension:cloned-outputs: Adds the clone output feature.
@jupyterlab/notebook-extension:code-console: Adds the notebook code consoles features.
@jupyterlab/notebook-extension:copy-output: Adds the copy cell outputs feature.
@jupyterlab/notebook-extension:kernel-status: Adds the notebook kernel status.
@jupyterlab/notebook-extension:cursor-position: Adds the notebook cursor position status.
@jupyterlab/notebook-extension:completer: Adds the code completion capability to notebooks.
@jupyterlab/notebook-extension:search: Adds search capability to notebooks.
@jupyterlab/notebook-extension:toc: Adds table of content capability to the notebooks
@jupyterlab/notebook-extension:language-server: Adds language server capability to the notebooks.
@jupyterlab/notebook-extension:update-raw-mimetype: Adds metadata form editor for raw cell mimetype.
@jupyterlab/notebook-extension:metadata-editor: Adds metadata form for full metadata editor.
@jupyterlab/notebook-extension:active-cell-tool: Adds active cell field in the metadata editor tab.
@jupyterlab/pluginmanager-extension:plugin: Enable or disable individual plugins.
@jupyterlab/rendermime-extension:plugin: Provides the render mime registry.
@jupyterlab/running-extension:plugin: Provides the running session managers.
@jupyterlab/settingeditor-extension:form-ui: Adds the interactive settings editor and provides its tracker.
@jupyterlab/settingeditor-extension:plugin: Adds the JSON settings editor and provides its tracker.
@jupyterlab/shortcuts-extension:shortcuts: Adds the keyboard shortcuts editor.
@jupyterlab/statusbar-extension:plugin: Provides the application status bar.
@jupyterlab/terminal-extension:plugin: Adds terminal and provides its tracker.
@jupyterlab/theme-dark-extension:plugin: Adds a dark theme.
@jupyterlab/theme-light-extension:plugin: Adds a light theme.
@jupyterlab/toc-extension:registry: Provides the table of contents registry.
@jupyterlab/toc-extension:tracker: Adds the table of content widget and provides its tracker.
@jupyterlab/tooltip-extension:manager: Provides the tooltip manager.
@jupyterlab/tooltip-extension:consoles: Adds the tooltip capability to consoles.
@jupyterlab/tooltip-extension:notebooks: Adds the tooltip capability to notebooks.
@jupyterlab/tooltip-extension:files: Adds the tooltip capability to file editors.
@jupyterlab/translation:translator: Provides the application translation object.
@jupyterlab/translation-extension:plugin: Adds translation commands and settings.
@jupyterlab/ui-components-extension:labicon-manager: Provides the icon manager.
@jupyterlab/ui-components-extension:form-renderer-registry: Provides the settings form renderer registry.

Core Tokens #

The core packages of JupyterLab provide many services for plugins. The tokens for these services are listed here, along with short descriptions of when you might want to use the services in your extensions.

@jupyterlab/application:IMimeDocumentTracker: A widget tracker for documents rendered using a mime renderer extension. Use this if you want to list and interact with documents rendered by such extensions.
@jupyterlab/application:ITreePathUpdater: A service to update the tree path.
@jupyterlab/application:ILayoutRestorer: A service providing application layout restoration functionality. Use this to have your activities restored across page loads.
@jupyterlab/application:IRouter: The URL router used by the application. Use this to add custom URL-routing for your extension (e.g., to invoke a command if the user navigates to a sub-path).
@jupyterlab/application:ITreeResolver: A service to resolve the tree path.
@jupyterlab/application:ILabShell: A service for interacting with the JupyterLab shell. The top-level application object also has a reference to the shell, but it has a restricted interface in order to be agnostic to different shell implementations on the application. Use this to get more detailed information about currently active widgets and layout state.
@jupyterlab/application:ILabStatus: A service for interacting with the application busy/dirty status. Use this if you want to set the application “busy” favicon, or to set the application “dirty” status, which asks the user for confirmation before leaving the application page.
@jupyterlab/application:IInfo: A service providing metadata about the current application, including disabled extensions and whether dev mode is enabled.
@jupyterlab/application:IPaths: A service providing information about various URLs and server paths for the current application. Use this service if you want to assemble URLs to use the JupyterLab REST API.
@jupyterlab/property-inspector:IPropertyInspectorProvider: A service to registry new widget in the property inspector side panel.
@jupyterlab/apputils:IKernelStatusModel: A service to register kernel session provider to the kernel status indicator.
@jupyterlab/apputils:ICommandPalette: A service for the application command palette in the left panel. Use this to add commands to the palette.
@jupyterlab/apputils:IWindowResolver: A service for a window resolver for the application. JupyterLab workspaces are given a name, which are determined using the window resolver. Require this if you want to use the name of the current workspace.
@jupyterlab/apputils:ISanitizer: A service for sanitizing HTML strings.
@jupyterlab/coreutils:ISettingRegistry: A service for the JupyterLab settings system. Use this if you want to store settings for your application. See “schemaDir” for more information.
@jupyterlab/coreutils:IStateDB: A service for the JupyterLab state database. Use this if you want to store data that will persist across page loads. See “state database” for more information.
@jupyterlab/apputils:ISplashScreen: A service for the splash screen for the application. Use this if you want to show the splash screen for your own purposes.
@jupyterlab/apputils:ISessionContextDialogs: A service for handling the session dialogs.
@jupyterlab/apputils:IThemeManager: A service for the theme manager for the application. This is used primarily in theme extensions to register new themes.
@jupyterlab/apputils:IToolbarWidgetRegistry: A registry for toolbar widgets. Require this if you want to build the toolbar dynamically from a data definition (stored in settings for example).
@jupyterlab/codemirror:IEditorLanguageRegistry: A registry for CodeMirror languages.
@jupyterlab/codemirror:IEditorThemeRegistry: A registry for CodeMirror theme.
@jupyterlab/codemirror:IEditorExtensionRegistry: A registry for CodeMirror extension factories.
@jupyterlab/codeeditor:IEditorServices: A service for the text editor provider for the application. Use this to create new text editors and host them in your UI elements.
@jupyterlab/codeeditor:IPositionModel: A service to handle an code editor cursor position.
@jupyterlab/completer:ICompletionProviderManager: A service for the completion providers management.
@jupyterlab/completer:IInlineCompleterFactory: A factory of inline completer widgets.
@jupyterlab/console:IContentFactory: A factory object that creates new code consoles. Use this if you want to create and host code consoles in your own UI elements.
@jupyterlab/console:IConsoleTracker: A widget tracker for code consoles. Use this if you want to be able to iterate over and interact with code consoles created by the application.
@jupyterlab/debugger:IDebugger: A debugger user interface.
@jupyterlab/debugger:IDebuggerHandler: A service for handling notebook debugger.
@jupyterlab/debugger:IDebuggerSidebar: A service for the debugger sidebar.
@jupyterlab/debugger:IDebuggerSources: A service to display sources in debug mode.
@jupyterlab/debugger:IDebuggerSourceViewer: A debugger source viewer.
@jupyterlab/debugger:IDebuggerConfig: A service to handle the debugger configuration.
@jupyterlab/docmanager:IDocumentManager: A service for the manager for all documents used by the application. Use this if you want to open and close documents, create and delete files, and otherwise interact with the file system.
@jupyterlab/docmanager:IDocumentWidgetOpener: A service to open a widget.
@jupyterlab/documentsearch:ISearchProviderRegistry: A service for a registry of search providers for the application. Plugins can register their UI elements with this registry to provide find/replace support.
@jupyterlab/filebrowser:IFileBrowserFactory: A factory object that creates file browsers. Use this if you want to create your own file browser (e.g., for a custom storage backend), or to interact with other file browsers that have been created by extensions.
@jupyterlab/filebrowser:IDefaultFileBrowser: A service for the default file browser.
@jupyterlab/filebrowser:IFileBrowserCommands: A token to ensure file browser commands are loaded.
@jupyterlab/fileeditor:IEditorTracker: A widget tracker for file editors. Use this if you want to be able to iterate over and interact with file editors created by the application.
@jupyterlab/htmlviewer:IHTMLViewerTracker: A widget tracker for rendered HTML documents. Use this if you want to be able to iterate over and interact with HTML documents viewed by the application.
@jupyterlab/application:IConnectionLost: A service for invoking the dialog shown when JupyterLab has lost its connection to the server. Use this if, for some reason, you want to bring up the “connection lost” dialog under new circumstances.
@jupyterlab/imageviewer:IImageTracker: A widget tracker for images. Use this if you want to be able to iterate over and interact with images viewed by the application.
@jupyterlab/inspector:IInspector: A service for adding contextual help to widgets (visible using “Show Contextual Help” from the Help menu). Use this to hook into the contextual help system in your extension.
@jupyterlab/launcher:ILauncher: A service for the application activity launcher. Use this to add your extension activities to the launcher panel.
@jupyterlab/logconsole:ILoggerRegistry: A service providing a logger infrastructure.
@jupyterlab/lsp:ILSPDocumentConnectionManager: Provides the virtual documents and language server connections service.
@jupyterlab/lsp:ILSPFeatureManager: Provides the language server feature manager. This token is required to register new client capabilities.
@jupyterlab/lsp:ILSPCodeExtractorsManager: Provides the code extractor manager. This token is required in your extension to register code extractor allowing the creation of multiple virtual document from an opened document.
@jupyterlab/lsp:IWidgetLSPAdapterTracker: Provides the WidgetLSPAdapter tracker. This token is required in your extension to track WidgetLSPAdapters.
@jupyterlab/mainmenu:IMainMenu: A service for the main menu bar for the application. Use this if you want to add your own menu items or provide implementations for standardized menu items for specific activities.
@jupyterlab/markdownviewer:IMarkdownViewerTracker: A widget tracker for markdown document viewers. Use this if you want to iterate over and interact with rendered markdown documents.
@jupyterlab/rendermime:IMarkdownParser: A service for rendering markdown syntax as HTML content.
@jupyterlab/rendermime:ILatexTypesetter: A service for the LaTeX typesetter for the application. Use this if you want to typeset math in your extension.
@jupyterlab/mermaid:IMermaidManager: a manager for rendering mermaid text-based diagrams
@jupyterlab/mermaid:IMermaidMarkdown: a manager for rendering mermaid text-based diagrams in markdown fenced code blocks
@jupyterlab/metadataform:IMetadataFormProvider: A service to register new metadata editor widgets.
@jupyterlab/notebook:IContentFactory: A factory object that creates new notebooks. Use this if you want to create and host notebooks in your own UI elements.
@jupyterlab/notebook:INotebookTracker: A widget tracker for notebooks. Use this if you want to be able to iterate over and interact with notebooks created by the application.
@jupyterlab/notebook:INotebookTools: A service for the “Notebook Tools” panel in the right sidebar. Use this to add your own functionality to the panel.
@jupyterlab/notebook:INotebookWidgetFactory: A service to create the notebook viewer.
@jupyterlab/pluginmanager:IPluginManager: A canary for plugin manager presence, with a method to open the plugin manager widget.
@jupyterlab/rendermime:IRenderMimeRegistry: A service for the rendermime registry for the application. Use this to create renderers for various mime-types in your extension. Many times it will be easier to create a “mime renderer extension” rather than using this service directly.
@jupyterlab/running:IRunningSessionManagers: A service to add running session managers.
@jupyterlab/settingeditor:ISettingEditorTracker: A widget tracker for the interactive setting editor. Use this if you want to be able to iterate over and interact with setting editors created by the application.
@jupyterlab/settingeditor:IJSONSettingEditorTracker: A widget tracker for the JSON setting editor. Use this if you want to be able to iterate over and interact with setting editors created by the application.
@jupyterlab/statusbar:IStatusBar: A service for the status bar on the application. Use this if you want to add new status bar items.
@jupyterlab/terminal:ITerminalTracker: A widget tracker for terminals. Use this if you want to be able to iterate over and interact with terminals created by the application.
@jupyterlab/toc:ITableOfContentsRegistry: A service to register table of content factory.
@jupyterlab/toc:ITableOfContentsTracker: A widget tracker for table of contents.
@jupyterlab/tooltip:ITooltipManager: A service for the tooltip manager for the application. Use this to allow your extension to invoke a tooltip.
@jupyterlab/translation:ITranslator: A service to translate strings.
@jupyterlab/ui-components:ILabIconManager: A service to register and request icons.
@jupyterlab/ui-components:IFormRendererRegistry: A service for settings form renderer registration.

Commands #

Add a Command to the Command Registry#

Perhaps the most common way to add functionality to JupyterLab is via commands. These are lightweight objects that include a function to execute combined with additional metadata, including how they are labeled and when they are to be enabled. The application has a single command registry, keyed by string command IDs, to which you can add your custom commands.

The commands added to the command registry can then be used to populate several of the JupyterLab user interface elements, including menus and the launcher.

Here is a sample block of code that adds a command to the application (given by app):

const commandID = 'my-command';
let toggled = false;

app.commands.addCommand(commandID, {
  label: 'My Cool Command',
  isEnabled: () => true,
  isVisible: () => true,
  isToggled: () => toggled,
  iconClass: 'some-css-icon-class',
  execute: () => {
    console.log(`Executed ${commandID}`);
    toggled = !toggled;
});

This example adds a new command, which, when triggered, calls the execute function. isEnabled indicates whether the command is enabled, and determines whether renderings of it are greyed out. isToggled indicates whether to render a check mark next to the command. isVisible indicates whether to render the command at all. iconClass specifies a CSS class which can be used to display an icon next to renderings of the command.

Each of isEnabled, isToggled, and isVisible can be either a boolean value or a function that returns a boolean value, in case you want to do some logic in order to determine those conditions.

Likewise, each of label and iconClass can be either a string value or a function that returns a string value.

There are several more options which can be passed into the command registry when adding new commands. These are documented here.

After a command has been added to the application command registry you can add them to various places in the application user interface, where they will be rendered using the metadata you provided.

For example, you can add a button to the Notebook toolbar to run the command with the CommandToolbarButtonComponent.

Add a Command to the Command Palette#

In order to add an existing, registered command to the command palette, you need to request the ICommandPalette token in your extension. Here is an example showing how to add a command to the command palette (given by palette):

palette.addItem({
  command: commandID,
  category: 'my-category',
  args: {}
});

The command ID is the same ID that you used when registering the command. You must also provide a category, which determines the subheading of the command palette in which to render the command. It can be a preexisting category (e.g., 'notebook'), or a new one of your own choosing.

The args are a JSON object that will be passed into your command’s functions at render/execute time. You can use these to customize the behavior of your command depending on how it is invoked. For instance, you can pass in args: { isPalette: true }. Your command label function can then check the args it is provided for isPalette, and return a different label in that case. This can be useful to make a single command flexible enough to work in multiple contexts.

Context Menu #

JupyterLab has an application-wide context menu available as app.contextMenu. The application context menu is shown when the user right-clicks, and is populated with menu items that are most relevant to the thing that the user clicked.

The context menu system determines which items to show based on CSS selectors. It propagates up the DOM tree and tests whether a given HTML element matches the CSS selector provided by a given command.

Items can be added in the context menu in two ways:

Using the settings - this is the preferred way as they are configurable by the user.
Using the API - this is for advanced cases like dynamic menu or semantic items.

Here is an example showing how to add a command to the application context menu using the settings.

{
  "jupyter.lab.menus": {
  "context": [
    {
      "command": "my-command",
      "selector": ".jp-Notebook",
      "rank": 500
    }
  ]
}

In this example, the command with id my-command is shown whenever the user right-clicks on a DOM element matching .jp-Notebook (that is to say, a notebook). The selector can be any valid CSS selector, and may target your own UI elements, or existing ones. A list of CSS selectors currently used by context menu commands is given in Commonly used CSS selectors.

Item must follow this definition:

      "context": {
        "title": "The application context menu.",
        "description": "List of context menu items.",
        "items": {
          "allOf": [
            {
              "$ref": "#/definitions/menuItem"
            },
            {
              "properties": {
                "selector": {
                  "description": "The CSS selector for the context menu item.",
                  "type": "string"
                }
              }
            }
          ]
        },
        "type": "array",
        "default": []
      }

where menuItem definition is:

{
  "menuItem": {
    "properties": {
      "args": {
        "description": "Command arguments",
        "type": "object"
      },
      "command": {
        "description": "Command id",
        "type": "string"
      },
      "disabled": {
        "description": "Whether the item is disabled or not",
        "type": "boolean",
        "default": false
      },
      "type": {
        "description": "Item type",
        "type": "string",
        "enum": [
          "command",
          "submenu",
          "separator"
        ],
        "default": "command"
      },
      "rank": {
        "description": "Item rank",
        "type": "number",
        "minimum": 0
      },
      "submenu": {
        "oneOf": [
          {
            "$ref": "#/definitions/menu"
          },
          {
            "type": "null"
          }
        ]
      }
    },
    "type": "object"
  }
}

The same example using the API is shown below. See the Lumino docs for the item creation options.

app.contextMenu.addItem({
  command: commandID,
  selector: '.jp-Notebook'
})

If you don’t want JupyterLab’s custom context menu to appear for your element, because you have your own right click behavior that you want to trigger, you can add the data-jp-suppress-context-menu data attribute to any node to have it and its children not trigger it.

For example, if you are building a custom React element, it would look like this:

function MyElement(props: {}) {
  return (
    <div data-jp-suppress-context-menu>
      <p>Hi</p>
      <p onContextMenu={() => {console.log("right clicked")}}>There</p>
    </div>
  )
}

Alternatively, you can use a ‘contextmenu’ event listener and call event.stopPropagation to prevent the application context menu handler from being called (it is listening in the bubble phase on the document). At this point you could show your own Lumino contextMenu, or simply stop propagation and let the system context menu be shown. This would look something like the following in a Widget subclass:

// In `onAfterAttach()`
this.node.addEventListener('contextmenu', this);

// In `handleEvent()`
case 'contextmenu':
  event.stopPropagation();

Copy Shareable Link #

The file browser provides a context menu item “Copy Shareable Link”. The desired behavior will vary by deployment and the users it serves. The file browser supports overriding the behavior of this item.

import {
  IFileBrowserFactory
} from '@jupyterlab/filebrowser';

import {
  JupyterFrontEnd, JupyterFrontEndPlugin
} from '@jupyterlab/application';


const shareFile: JupyterFrontEndPlugin<void> = {
  activate: activateShareFile,
  id: commandID,
  requires: [IFileBrowserFactory],
  autoStart: true
};

function activateShareFile(
  app: JupyterFrontEnd,
  factory: IFileBrowserFactory
): void {
  const { commands } = app;
  const { tracker } = factory;

  commands.addCommand('filebrowser:share-main', {
    execute: () => {
      const widget = tracker.currentWidget;
      if (!widget) {
        return;
      }
      const path = encodeURI(widget.selectedItems().next().path);
      // Do something with path.
    },
    isVisible: () =>
      tracker.currentWidget &&
      Array.from(tracker.currentWidget.selectedItems()).length === 1,
    iconClass: 'jp-MaterialIcon jp-LinkIcon',
    label: 'Copy Shareable Link'
  });
}

Note that an extension providing a replacement plugin like this must either automatically disable the replaced core plugin or the user must disable the core plugin manually:

jupyter labextension disable @jupyterlab/filebrowser-extension:share-file

Icons #

See Reusing JupyterLab UI

Keyboard Shortcuts #

There are two ways of adding keyboard shortcuts in JupyterLab. If you don’t want the shortcuts to be user-configurable, you can add them directly to the application command registry:

app.commands.addKeyBinding({
  command: commandID,
  args: {},
  keys: ['Accel T'],
  selector: '.jp-Notebook'
});

In this example my-command command is mapped to Accel T, where Accel corresponds to Cmd on a Mac and Ctrl on Windows and Linux computers.

The behavior for keyboard shortcuts is very similar to that of the context menu: the shortcut handler propagates up the DOM tree from the focused element and tests each element against the registered selectors. If a match is found, then that command is executed with the provided args. Full documentation for the options for addKeyBinding can be found here.

JupyterLab also provides integration with its settings system for keyboard shortcuts. Your extension can provide a settings schema with a jupyter.lab.shortcuts key, declaring default keyboard shortcuts for a command:

{
  "jupyter.lab.shortcuts": [
    {
      "command": "my-command",
      "keys": ["Accel T"],
      "selector": ".jp-mod-searchable"
    }
  ]
}

Shortcuts added to the settings system will be editable by users.

From Jupyterlab version 3.1 onwards, it is possible to execute multiple commands with a single shortcut. This requires you to define a keyboard shortcut for apputils:run-all-enabled command:

{
  "command": "apputils:run-all-enabled",
  "keys": ["Accel T"],
  "args": {
      "commands": [
          "my-command-1",
          "my-command-2"
      ],
      "args": [
          {},
          {}
        ]
    },
  "selector": "body"
}

In this example my-command-1 and my-command-2 are passed in args of apputils:run-all-enabled command as commands list. You can optionally pass the command arguments of my-command-1 and my-command-2 in args of apputils:run-all-enabled command as args list.

Launcher #

As with menus, keyboard shortcuts, and the command palette, new items can be added to the application launcher via commands. You can do this by requesting the ILauncher token in your extension:

launcher.add({
  command: commandID,
  category: 'Other',
  rank: 0
});

In addition to providing a command ID, you also provide a category in which to put your item, (e.g. ‘Notebook’, or ‘Other’), as well as a rank to determine its position among other items.

Jupyter Front-End Shell #

The Jupyter front-end shell is used to add and interact with content in the application. The IShell interface provides an add() method for adding widgets to the application. In JupyterLab, the application shell consists of:

A top area for things like top-level toolbars and information.
A menu area for top-level menus, which is collapsed into the top area in multiple-document mode and put below it in single-document mode.
left and right sidebar areas for collapsible content.
A main work area for user activity.
A down area for information content; like log console, contextual help.
A bottom area for things like status bars.
A header area for custom elements.

Top Area#

The top area is intended to host most persistent user interface elements that span the whole session of a user. A toolbar named TopBar is available on the right of the main menu bar. For example, JupyterLab adds a user dropdown to that toolbar when started in collaborative mode.

See generic toolbars to see how to add a toolbar or a custom widget to a toolbar.

You can use a numeric rank to control the ordering of top bar items in the settings; see Toolbar definitions.

JupyterLab adds a spacer widget to the top bar at rank 50 by default. You can then use the following guidelines to place your items:

rank <= 50 to place items to the left side in the top bar
rank > 50 to place items to the right side in the top bar

Left/Right Areas#

The left and right sidebar areas of JupyterLab are intended to host more persistent user interface elements than the main area. That being said, extension authors are free to add whatever components they like to these areas. The outermost-level of the object that you add is expected to be a Lumino Widget, but that can host any content you like (such as React components).

As an example, the following code executes an application command to a terminal widget and then adds the terminal to the right area:

app.commands
  .execute('terminal:create-new')
  .then((terminal: WidgetModuleType.Terminal) => {
    app.shell.add(terminal, 'right');
  });

You can use a numeric rank to control the ordering of the left and right tabs:

app.shell.add(terminal, 'left', {rank: 600});

The recommended ranges for this rank are:

0-500: reserved for first-party JupyterLab extensions.
501-899: reserved for third-party extensions.
900: The default rank if none is specified.
1000: The JupyterLab extension manager.

Main Menu #

There are two ways to extend JupyterLab’s main menu.

Using the settings - this is the preferred way as they are configurable by the user.
Using the API - this is for advanced cases like dynamic menu or semantic items.

Settings-defined menu#

JupyterLab provides integration with its settings system for menu definitions. Your extension can provide a settings schema with a jupyter.lab.menus key, declaring default menus. You don’t need to set anything in the TypeScript code (except the command definitions).

To add a new menu with your extension command:

{
  "jupyter.lab.menus": {
  "main": [
    {
      "id": "jp-mainmenu-myextension",
      "label": "My Menu",
      "items": [
        {
          "command": "my-command",
          "rank": 500
        }
      ],
      "rank": 100
    }
  ]
}

The menu item label will be set with the command label. For menus (and submenus), the label needs to be set explicitly with the label property.

Menu and item have a rank that will determine the elements order.

To add a new entry in an existing menu:

{
  "jupyter.lab.menus": {
  "main": [
    {
      "id": "jp-mainmenu-file",
      "items": [
        {
          "command": "my-command",
          "rank": 500
        }
      ]
    }
  ]
}

Here is the list of default menu ids:

File menu: jp-mainmenu-file
- New file submenu: jp-mainmenu-file-new
Edit menu: jp-mainmenu-edit
View menu: jp-mainmenu-view
- Appearance submenu: jp-mainmenu-view-appearance
Run menu: jp-mainmenu-run
Kernel menu: jp-mainmenu-kernel
Tabs menu: jp-mainmenu-tabs
Settings menu: jp-mainmenu-settings
Help menu: jp-mainmenu-help

The default main menu is defined in the mainmenu-extension package settings.

A menu must respect the following schema:

      "main": {
        "title": "Main menu entries",
        "description": "List of menu items to add to the main menubar.",
        "items": {
          "$ref": "#/definitions/menu"
        },
        "type": "array",
        "default": []
      },

And an item must follow:

{
  "menu": {
    "properties": {
      "disabled": {
        "description": "Whether the menu is disabled or not",
        "type": "boolean",
        "default": false
      },
      "icon": {
        "description": "Menu icon id",
        "type": "string"
      },
      "id": {
        "description": "Menu unique id",
        "oneOf": [
          {
            "type": "string",
            "enum": [
              "jp-menu-file",
              "jp-menu-file-new",
              "jp-menu-edit",
              "jp-menu-help",
              "jp-menu-kernel",
              "jp-menu-run",
              "jp-menu-settings",
              "jp-menu-view",
              "jp-menu-tabs"
            ]
          },
          {
            "type": "string",
            "pattern": "[a-z][a-z0-9\\-_]+"
          }
        ]
      },
      "items": {
        "description": "Menu items",
        "type": "array",
        "items": {
          "$ref": "#/definitions/menuItem"
        }
      },
      "label": {
        "description": "Menu label",
        "type": "string"
      },
      "mnemonic": {
        "description": "Mnemonic index for the label",
        "type": "number",
        "minimum": -1,
        "default": -1
      },
      "rank": {
        "description": "Menu rank",
        "type": "number",
        "minimum": 0
      }
    },
    "required": [
      "id"
    ],
    "type": "object"
  }
}

Menus added to the settings system will be editable by users using the mainmenu-extension settings. In particular, they can be disabled at the item or the menu level by setting the property disabled to true.

API-defined menu#

To use the API, you should request the IMainMenu token for your extension.

There are three main ways to extend:

You can add your own menu to the menu bar.
You can add new commands to the existing menus.
You can register your extension with one of the existing semantic menu items.

Adding a New Menu#

To add a new menu to the menu bar, you need to create a new Lumino menu.

You can then add commands to the menu in a similar way to the command palette, and add that menu to the main menu bar:

const menu = new Menu({ commands: app.commands });
menu.addItem({
  command: commandID,
  args: {},
});

mainMenu.addMenu(menu, { rank: 40 });

As with the command palette, you can optionally pass in args to customize the rendering and execution behavior of the command in the menu context.

Adding a New Command to an Existing Menu#

In many cases you will want to add your commands to the existing JupyterLab menus rather than creating a separate menu for your extension. Because the top-level JupyterLab menus are shared among many extensions, the API for adding items is slightly different. In this case, you provide a list of commands and a rank, and these commands will be displayed together in a separate group within an existing menu.

For instance, to add a command group with firstCommandID and secondCommandID to the File menu, you would do the following:

mainMenu.fileMenu.addGroup([
  {
    command: firstCommandID,
  },
  {
    command: secondCommandID,
  }
], 40 /* rank */);

Registering a Semantic Menu Item#

There are some commands in the JupyterLab menu system that are considered common and important enough that they are treated differently.

For instance, we anticipate that many activities may want to provide a command to close themselves and perform some cleanup operation (like closing a console and shutting down its kernel). Rather than having a proliferation of similar menu items for this common operation of “closing-and-cleanup”, we provide a single command that can adapt itself to this use case, which we term a “semantic menu item”. For this example, it is the File Menu closeAndCleaners set.

Here is an example of using the closeAndCleaners semantic menu item:

mainMenu.fileMenu.closeAndCleaners.add({
  id: 'notebook:close-and-shutdown',
  isEnabled: (w: Widget) => tracker.currentWidget !== null && tracker.has(w)
});

In this example, tracker is a Widget Tracker, which allows the menu item to determine whether to delegate the menu command to your activity, and id is a the command identifier.

More examples for how to register semantic menu items are found throughout the JupyterLab code base. The available semantic menu items are:

IEditMenu.IUndoer: an activity that knows how to undo and redo.
IEditMenu.IClearer: an activity that knows how to clear its content.
IEditMenu.IGoToLiner: an activity that knows how to jump to a given line.
IFileMenu.ICloseAndCleaner: an activity that knows how to close and clean up after itself.
IFileMenu.IConsoleCreator: an activity that knows how to create an attached code console for itself.
IHelpMenu.IKernelUser: an activity that knows how to get a related kernel session.
IKernelMenu.IKernelUser: an activity that can perform various kernel-related operations.
IRunMenu.ICodeRunner: an activity that can run code from its content.
IViewMenu.IEditorViewer: an activity that knows how to set various view-related options on a text editor that it owns.

Status Bar #

JupyterLab’s status bar is intended to show small pieces of contextual information. Like the left and right areas, it only expects a Lumino Widget, which might contain any kind of content. Since the status bar has limited space, you should endeavor to only add small widgets to it.

The following example shows how to place a status item that displays the current “busy” status for the application. This information is available from the ILabStatus token, which we reference by a variable named labStatus. We place the statusWidget in the middle of the status bar. When the labStatus busy state changes, we update the text content of the statusWidget to reflect that.

const statusWidget = new Widget();
labStatus.busySignal.connect(() => {
  statusWidget.node.textContent = labStatus.isBusy ? 'Busy' : 'Idle';
});
statusBar.registerStatusItem('lab-status', {
  align: 'middle',
  item: statusWidget
});

Toolbar Registry #

JupyterLab provides an infrastructure to define and customize toolbar widgets from the settings, which is similar to that defining the context menu and the main menu bar.

Document Widgets#

A typical example is the notebook toolbar as in the snippet below:

function activatePlugin(
  app: JupyterFrontEnd,
  // ...
  toolbarRegistry: IToolbarWidgetRegistry | null,
  settingRegistry: ISettingRegistry | null
): NotebookWidgetFactory.IFactory {
  const { commands } = app;
  let toolbarFactory:
    | ((widget: NotebookPanel) => DocumentRegistry.IToolbarItem[])
    | undefined;

  // Register notebook toolbar specific widgets
  if (toolbarRegistry) {
    toolbarRegistry.registerFactory<NotebookPanel>(FACTORY, 'cellType', panel =>
      ToolbarItems.createCellTypeItem(panel, translator)
    );

    toolbarRegistry.registerFactory<NotebookPanel>(
      FACTORY,
      'kernelStatus',
      panel => Toolbar.createKernelStatusItem(panel.sessionContext, translator)
    );
    // etc...

    if (settingRegistry) {
      // Create the factory
      toolbarFactory = createToolbarFactory(
        toolbarRegistry,
        settingRegistry,
        // Factory name
        FACTORY,
        // Setting id in which the toolbar items are defined
        '@jupyterlab/notebook-extension:panel',
        translator
      );
    }
  }

  const factory = new NotebookWidgetFactory({
    name: FACTORY,
    fileTypes: ['notebook'],
    modelName: 'notebook',
    defaultFor: ['notebook'],
    // ...
    toolbarFactory,
    translator: translator
  });
  app.docRegistry.addWidgetFactory(factory);

The registry registerFactory method allows an extension to provide special widget for a unique pair (factory name, toolbar item name). Then the helper createToolbarFactory can be used to extract the toolbar definition from the settings and build the factory to pass to the widget factory.

The default toolbar items can be defined across multiple extensions by providing an entry in the "jupyter.lab.toolbars" mapping. For example for the notebook panel:

The settings registry will merge those definitions from settings schema with any user-provided overrides (customizations) transparently and save them under the toolbar property in the final settings object. The toolbar list will be used to create the toolbar. Both the source settings schema and the final settings object are identified by the plugin ID passed to createToolbarFactory. The user can customize the toolbar by adding new items or overriding existing ones (like providing a different rank or adding "disabled": true to remove the item).

Note

You need to set jupyter.lab.transform to true in the plugin id that will gather all items.

The current widget factories supporting the toolbar customization are:

Notebook: Notebook panel toolbar
Cell: Cell toolbar
Editor: Text editor toolbar
HTML Viewer: HTML Viewer toolbar
CSVTable: CSV (Comma Separated Value) Viewer toolbar
TSVTable: TSV (Tabulation Separated Value) Viewer toolbar

{
  "toolbarItem": {
    "properties": {
      "name": {
        "title": "Unique name",
        "type": "string"
      },
      "args": {
        "title": "Command arguments",
        "type": "object"
      },
      "command": {
        "title": "Command id",
        "type": "string",
        "default": ""
      },
      "disabled": {
        "title": "Whether the item is ignored or not",
        "type": "boolean",
        "default": false
      },
      "icon": {
        "title": "Item icon id",
        "description": "If defined, it will override the command icon",
        "type": "string"
      },
      "label": {
        "title": "Item label",
        "description": "If defined, it will override the command label",
        "type": "string"
      },
      "caption": {
        "title": "Item caption",
        "description": "If defined, it will override the command caption",
        "type": "string"
      },
      "type": {
        "title": "Item type",
        "type": "string",
        "enum": [
          "command",
          "spacer"
        ]
      },
      "rank": {
        "title": "Item rank",
        "type": "number",
        "minimum": 0,
        "default": 50
      }
    },
    "required": [
      "name"
    ],
    "additionalProperties": false,
    "type": "object"
  }
}

Widget Tracker #

Often extensions will want to interact with documents and activities created by other extensions. For instance, an extension may want to inject some text into a notebook cell, or set a custom keymap, or close all documents of a certain type. Actions like these are typically done by widget trackers. Extensions keep track of instances of their activities in WidgetTrackers, which are then provided as tokens so that other extensions may request them.

For instance, if you want to interact with notebooks, you should request the INotebookTracker token. You can then use this tracker to iterate over, filter, and search all open notebooks. You can also use it to be notified via signals when notebooks are added and removed from the tracker.

Widget tracker tokens are provided for many activities in JupyterLab, including notebooks, consoles, text files, mime documents, and terminals. If you are adding your own activities to JupyterLab, you might consider providing a WidgetTracker token of your own, so that other extensions can make use of it.

Completion Providers #

Both code completer and inline completer can be extended by registering an (inline) completion provider on the completion manager provided by the ICompletionProviderManager token.

Code Completer#

A minimal code completion provider needs to implement the fetch and isApplicable methods, and define a unique identifier property, but the ICompletionProvider interface allows for much more extensive customization of the completer.

import { ICompletionProviderManager, ICompletionProvider } from '@jupyterlab/completer';

class MyProvider implements ICompletionProvider {
  readonly identifier = 'my-provider';

  async isApplicable(context) {
    return true;
  }

  async fetch(request, context) {
    return {
      start: request.offset,
      end: request.offset,
      items: [
        { label: 'option 1' },
        { label: 'option 2' }
      ]
    };
  }
}

const plugin: JupyterFrontEndPlugin<void> = {
  id: 'my-completer-extension:provider',
  autoStart: true,
  requires: [ICompletionProviderManager],
  activate: (app: JupyterFrontEnd, manager: ICompletionProviderManager): void => {
    const provider = new MyProvider();
    manager.registerProvider(provider);
  }
};

A more detailed example is provided in the extension-examples repository.

For an example of an extensively customised completion provider, see the jupyterlab-lsp extension.

Inline Completer#

A minimal inline completion provider extension would only implement the required method fetch and define identifier and name properties, but a number of additional fields can be used for enhanced functionality, such as streaming, see the IInlineCompletionProvider documentation.

import { ICompletionProviderManager, IInlineCompletionProvider } from '@jupyterlab/completer';

class MyInlineProvider implements IInlineCompletionProvider {
  readonly identifier = 'my-provider';
  readonly name = 'My provider';

  async fetch(request, context) {
    return {
      items: [
        { insertText: 'suggestion 1' },
        { insertText: 'suggestion 2' }
      ]
    };
  }
}

const plugin: JupyterFrontEndPlugin<void> = {
  id: 'my-completer-extension:inline-provider',
  autoStart: true,
  requires: [ICompletionProviderManager],
  activate: (app: JupyterFrontEnd, manager: ICompletionProviderManager): void => {
    const provider = new MyInlineProvider();
    manager.registerInlineProvider(provider);
  }
};

For an example of an inline completion provider with streaming support, see jupyterlab-transformers-completer.

State Database #

The state database can be accessed by importing IStateDB from @jupyterlab/statedb and adding it to the list of requires for a plugin:

const id = 'foo-extension:IFoo';

const IFoo = new Token<IFoo>(id);

interface IFoo {}

class Foo implements IFoo {}

const plugin: JupyterFrontEndPlugin<IFoo> = {
  id,
  autoStart: true,
  requires: [IStateDB],
  provides: IFoo,
  activate: (app: JupyterFrontEnd, state: IStateDB): IFoo => {
    const foo = new Foo();
    const key = `${id}:some-attribute`;

    // Load the saved plugin state and apply it once the app
    // has finished restoring its former layout.
    Promise.all([state.fetch(key), app.restored])
      .then(([saved]) => { /* Update `foo` with `saved`. */ });

    // Fulfill the plugin contract by returning an `IFoo`.
    return foo;
  }
};

LSP Features #

JupyterLab provides an infrastructure to communicate with the language servers. If the LSP services are activated and users have language servers installed, JupyterLab will start the language servers for the language of the opened notebook or file. Extension authors can access the virtual documents and the associated LSP connection of opened document by requiring the ILSPDocumentConnectionManager token from @jupyterlab/lsp.

Here is an example for making requests to the language server.

const plugin: JupyterFrontEndPlugin<void> = {
  id,
  autoStart: true,
  requires: [ILSPDocumentConnectionManager],
  activate: async (app: JupyterFrontEnd, manager: ILSPDocumentConnectionManager): Promise<void> => {

    // Get the path to the opened notebook of file
    const path = ...

    // Get the widget adapter of opened document
    const adapter = manager.adapters.get(path);
    if (!adapter) {
      return
    }
    // Get the associated virtual document of the opened document
    const virtualDocument = adapter.virtualDocument;

    // Get the LSP connection of the virtual document.
    const connection = manager.connections.get(virtualDocument.uri);
    ...
    // Send completion request to the language server
    const response = await connection.clientRequests['textDocument/completion'].request(params);
    ...
  }
};

Occasionally, LSP extensions include a CodeMirror extension to modify the code editor. In those cases, you can follow this example:

const renamePlugin: JupyterFrontEndPlugin<void> = {
  id,
  autoStart: true,
  requires: [ILSPDocumentConnectionManager, ILSPFeatureManager, IWidgetLSPAdapterTracker],
  activate: (app: JupyterFrontEnd, connectionManager: ILSPDocumentConnectionManager, featureManager: ILSPFeatureManager, tracker: IWidgetLSPAdapterTracker) => {
    const FEATURE_ID = "rename_symbol";
    const extensionFactory: EditorAdapter.ILSPEditorExtensionFactory = {
      name: FEATURE_ID,
      factory: (options) =>  {
        const { editor, widgetAdapter } = options;

        // Get the editor
        const ceEditor: CodeEditor.IEditor | null = editor.getEditor();
        if (!ceEditor) {
          return null;
        }

        // Get the associated virtual document of the opened document
        if (!widgetAdapter.virtualDocument) {
          return null;
        }

        // Get the LSP connection of the virtual document.
        const connection = connectionManager.connections.get(widgetAdapter.virtualDocument.uri);
        if (!connection || !connection.provides('renameProvider')) {
          return null;
        }

        // Create a CodeMirror extension that listens for double click, gets the
        // selected code and makes a LSP request to rename it and prints the results.
        const ext = EditorView.domEventHandlers({ dblclick: (e, view) => {
          const range = ceEditor.getSelection();
            const res = connection.clientRequests['textDocument/rename'].request({
              newName: "test",
              position: { line: range.start.line, character: range.start.column },
              textDocument: { uri: widgetAdapter.virtualDocument!.uri }
            });

            res.then(value => {
              console.debug(value);
            }).catch(e => console.error);
        }});

        // Wrap the CodeMirror extension in the extension registry object.
        return EditorExtensionRegistry.createImmutableExtension(ext);
      }
    }

    // Register the extension with the LSP feature
    featureManager.register({
      id: FEATURE_ID,
      extensionFactory
    });
  }
};

Common Extension Points#

Add a Command to the Command Registry#

Add a Command to the Command Palette#

Top Area#

Left/Right Areas#

Settings-defined menu#

API-defined menu#

Adding a New Menu#

Adding a New Command to an Existing Menu#

Registering a Semantic Menu Item#

Document Widgets#

Generic Widget with Toolbar#

Code Completer#

Inline Completer#