May 1, 2019

773 words 4 mins read



A browser based code editor

repo name microsoft/monaco-editor
repo link
language JavaScript
size (curr.) 8230 kB
stars (curr.) 19125
created 2016-06-07
license MIT License

Monaco Editor

Build Status

The Monaco Editor is the code editor which powers VS Code, with the features better described here.

Please note that this repository contains no source code for the code editor, it only contains the scripts to package everything together and ship the monaco-editor npm module.


Try it out

Try the editor out on our website.


$ npm install monaco-editor

You will get:

  • inside esm: ESM version of the editor (compatible with e.g. webpack)
  • inside dev: AMD bundled, not minified
  • inside min: AMD bundled, and minified
  • inside min-maps: source maps for min
  • monaco.d.ts: this specifies the API of the editor (this is what is actually versioned, everything else is considered private and might break with any release).

It is recommended to develop against the dev version, and in production to use the min version.



Create issues in this repository for anything related to the Monaco Editor. Always mention the version of the editor when creating issues and the browser you’re having trouble in. Please search for existing issues to avoid duplicates.


What is the relationship between VS Code and the Monaco Editor?

The Monaco Editor is generated straight from VS Code’s sources with some shims around services the code needs to make it run in a web browser outside of its home.

What is the relationship between VS Code’s version and the Monaco Editor’s version?

None. The Monaco Editor is a library and it reflects directly the source code.

I’ve written an extension for VS Code, will it work on the Monaco Editor in a browser?


Note: If the extension is fully based on the LSP and if the language server is authored in JavaScript, then it would be possible.

Why all these web workers and why should I care?

Language services create web workers to compute heavy stuff outside of the UI thread. They cost hardly anything in terms of resource overhead and you shouldn’t worry too much about them, as long as you get them to work (see above the cross-domain case).

What is this loader.js? Can I use require.js?

It is an AMD loader that we use in VS Code. Yes.

I see the warning “Could not create web worker”. What should I do?

HTML5 does not allow pages loaded on file:// to create web workers. Please load the editor with a web server on http:// or https:// schemes. Please also see the cross-domain case above.

Is the editor supported in mobile browsers or mobile web app frameworks?


Why doesn’t the editor support TextMate grammars?

  • All the regular expressions in TM grammars are based on oniguruma, a regular expression library written in C.
  • The only way to interpret the grammars and get anywhere near original fidelity is to use the exact same regular expression library (with its custom syntax constructs).
  • In VSCode, our runtime is node.js and we can use a node native module that exposes the library to JavaScript.
  • In Monaco, we are constrained to a browser environment where we cannot do anything similar.
  • We have experimented with Emscripten to compile the C library to asm.js, but performance was very poor even in Firefox (10x slower) and extremely poor in Chrome (100x slower).
  • We can revisit this once WebAssembly gets traction in the major browsers, but we will still need to consider the browser matrix we support, i.e. if we support IE11 and only Edge will add WebAssembly support, what will the experience be in IE11, etc.

What about IE 11 support?

  • The Monaco Editor no longer supports IE 11. The last version that was tested on IE 11 is 0.18.1.

Development setup


Code of Conduct

This project has adopted the Microsoft Open Source Code of Conduct. For more information see the Code of Conduct FAQ or contact with any additional questions or comments.


Licensed under the MIT License.

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