tsx

What is tsx?

The tsx npm package is a CLI tool for running TypeScript and TSX files directly without pre-compilation. It's essentially a TypeScript execution and REPL for node.js, similar to how `node` works for JavaScript. It allows developers to quickly run scripts and prototypes written in TypeScript, including support for TSX (TypeScript with JSX syntax), which is commonly used in React development.

What are tsx's main functionalities?

Execute TypeScript files directly

Allows you to run a TypeScript file directly from the command line without needing to compile it first. This is particularly useful for quick scripts or during development.

tsx script.ts

REPL mode

Launches a REPL (Read-Eval-Print Loop) where you can type and execute TypeScript code interactively. This is useful for testing small snippets of code quickly.

tsx

Support for TSX

Enables execution of TSX files, which is TypeScript with JSX syntax. This is particularly useful for React developers who want to test components or scripts that include JSX.

tsx component.tsx

Other packages similar to tsx

ts-node

ts-node is a very popular package that offers similar functionality to tsx. It provides the ability to execute TypeScript files directly and use TypeScript in a REPL environment. ts-node is widely used in the TypeScript community for development and scripting. Compared to tsx, ts-node has been around longer and has a larger user base, but both aim to simplify the TypeScript development workflow by removing the compilation step.

esbuild-runner

esbuild-runner offers a way to run TypeScript (and JavaScript) files using the esbuild bundler/compiler. It's focused on providing extremely fast compilation and execution, leveraging esbuild's performance. While esbuild-runner and tsx share the goal of simplifying the execution of TypeScript files, esbuild-runner emphasizes speed and is part of the broader ecosystem around the esbuild project.

README

tsx

Node.js enhanced with esbuild to run TypeScript & ESM

Features

• Blazing fast on-demand TypeScript & ESM compilation
• Works in both CommonJS and ESM packages
• Supports next-gen TypeScript extensions (.cts & .mts)
• Supports node: import prefixes
• Hides experimental feature warnings
• TypeScript REPL
• Tested on Linux & Windows with Node.js v12~18

Install

npm install --save-dev tsx

Install globally

Install it globally to use it anywhere, outside of your npm project, without npx.

npm install --global tsx

Usage

Note: Commands are prefixed with npx to execute the tsx binary, but it's not necessary if globally installed or when using it in the script object in package.json

Run TypeScript / ESM / CJS module

Pass in a file to run:

npx tsx ./file.ts

Watch mode

Run file and automatically re-run on changes.

All imported files are watched except from the following directories: node_modules, bower_components, vendor, dist, and .* (hidden directories).

Press Return to manually re-run.

npx tsx watch ./file.ts

REPL

Start a TypeScript REPL by running tsx with no arguments.

npx tsx

Cache

Modules transformations are cached in the system cache directory (TMPDIR). Transforms are cached by content hash so duplicate dependencies are not re-transformed.

Set the --no-cache flag to disable the cache:

npx tsx --no-cache ./file.ts

Node.js Loader

tsx is a standalone binary used in-place of Node.js, but sometimes you'll want to use node directly. For example, when adding TypeScript & ESM support to Node.js binaries.

To use tsx with Node.js, pass it into the --loader flag.

Note: Node.js's experimental feature warnings will not be suppressed when used as a loader

# As a CLI flag
node --loader tsx ./file.ts

# As an environment variable
NODE_OPTIONS='--loader tsx' node ./file.ts

If you're looking to use the -r, --require flag, you can use @esbuild-kit/cjs-loader but transformations will not be applied to dynamic import()s.

Dependencies

• @esbuild-kit/esm-loader - Node.js Loader to transform TypeScript to ESM.

• @esbuild-kit/cjs-loader - Node.js requie() hook to transform TypeScript & ESM to CommonJS.

FAQ

Does it do type-checking?

No, esbuild does not support type checking.

It's recommended to run TypeScript separately as a command (tsc --noEmit) or via IDE IntelliSense.

How is tsx different from ts-node?

They are both tools to run TypeScript files.

The main difference is that tsx is powered by esbuild for blazing fast TypeScript compilation. Whereas ts-node uses the TypeScript compiler, which is not as fast.

Because esbuild doesn't do type checking, tsx is more equivalent to ts-node --transpileOnly.

If you migrated from ts-node, please share your performance gains here!