1 unstable release

0.1.0 Nov 6, 2023

#757 in WebAssembly

23 downloads per month

MIT license

2.5K SLoC

Rust 2K SLoC // 0.0% comments TypeScript 285 SLoC // 0.1% comments JavaScript 102 SLoC JSX 27 SLoC TSX 27 SLoC

Rust Build Status TypeScript Build Status

Well, Does it Throw?

TLDR; This is a blazingly fast lsp server to find throw statements in your javascript code. It's written in Rust and based on SWC 🔥. It works for most ECMAScript files, such as .ts, .js, .tsx and .jsx.

Check it out in action:


Also supports call expressions:



Maybe you're working on a large codebase riddled with throw statements everywhere, and you want a better control flow. Or perhaps you're just curious about how many throw statements you have in your codebase. This simple tool can help you with that.

Untyped throw statements can be a pain for those who come from languages like Go, where errors are typically values and first-class citizens. Even Rust has the Result type. Knowing where throw statements are in your codebase might be helpful, even if their return types aren't directly supported.

This extension may not be for everyone, but it's definitely for me. I hope you find it useful too.


Platform Installation
VsCode Marketplace
Neovim Neovim Installation Docs
LSP Server NPM
JetBrains Marketplace

This extension is built with security in mind. It doesn't send any data to any third party servers. All publishes are done via a signed immutable commit from the CI pipeline.

The core of the code is written in Rust, and the LSP implementation for VsCode is written in Typescript. The Rust code is compiled to WASM and bundled with the VsCode extension. The extension is published to the VsCode marketplace, and the Rust code is published to crates.io.


For a usage and configuration guide, check out the usage page!


  • This extension is still in its early stages. It's not perfect, but hope to gain sufficient ECMAScript coverage over time.
  • Currently, it only supports ECMAScript files and the following file types: .ts, .js, .tsx and .jsx.
  • Call expression tracing (Aka "Calls to Throws") is now set to one level deep. Hope to make this configurable in the future!

To view all known limitations, please see the issues page.


Contributions are certainly welcome! Please open an issue or submit a PR. If you find a use case that isn't supported yet, please search the open issues and open a new one if it doesn't exist.

Dev Setup

Everything can be found in the CONTRIBUTING.md file!

Feedback & Suggestions

Please use the GitHub discussions tab to provide feedback and suggestions. Thanks!



MIT - See LICENSE for more information.


~193K SLoC