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Language services for CSS, LESS and SCSS

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The vscode-css-languageservice contains the language smarts behind the CSS, LESS and SCSS editing experience of Visual Studio Code and the Monaco editor.

  • doValidation analyses an input string and returns syntax and lint errors.
  • doComplete provides completion proposals for a given location.
  • doHover provides a hover text for a given location.
  • findDefinition finds the definition of the symbol at the given location.
  • findReferences finds all references to the symbol at the given location.
  • findDocumentHighlights finds all symbols connected to the given location.
  • findDocumentSymbols provides all symbols in the given document
  • doCodeActions evaluates code actions for the given location, typically to fix a problem.
  • findColorSymbols evaluates all color symbols in the given document
  • doRename renames all symbols connected to the given location.
  • getFoldingRanges returns folding ranges in the given document.


npm install --save vscode-css-languageservice


For the complete API see cssLanguageService.ts and cssLanguageTypes.ts


  • clone this repo, run yarn
  • yarn test to compile and run tests

How can I run and debug the service?

  • open the folder in VSCode.
  • set breakpoints, e.g. in cssCompletion.ts
  • run the Unit tests from the run viewlet and wait until a breakpoint is hit: image

How can I run and debug the service inside an instance of VSCode?

  • run VSCode out of sources setup as described here:
  • use yarn link vscode-css-languageservice in vscode/extensions/css-language-features/server to run VSCode with the latest changes from vscode-css-languageservice
  • run VSCode out of source (vscode/scripts/|bat) and open a .css file
  • in VSCode window that is open on the vscode-css-languageservice sources, run command Debug: Attach to Node process and pick the code-oss process with the css-language-features path image
  • set breakpoints, e.g. in cssCompletion.ts
  • in the instance run from sources, invoke code completion in the .css file

Note: All CSS entities (properties, at-rules, etc) are sourced from and transpiled here. For adding new property or fixing existing properties' completion/hover description, please open PR there).


(MIT License)

Copyright 2016, 20 Microsoft

With the exceptions of build/mdn-documentation.js, which is built upon content from Mozilla Developer Network and distributed under CC BY-SA 2.5.


CSS, LESS & SCSS language service extracted from VSCode to be reused, e.g in the Monaco editor.




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