esbuild-dev

A reloading dev server for server side TypeScript projects. Compiles TypeScript real fast, on demand, using require.extensions, and restarts the server when things change. Similar to, and inspired by ts-node-dev.

Features

Builds and runs TypeScript really fast (using esbuild)
Incrementally rebuilds only what has changed in the --watch mode, and restarts the process when files change
Supervises the node.js process with --supervise to keep incremental context around on process crash, and can restart on demand in the --commands mode
Plays nice with node.js command line flags like --inspect or --prof

Status

Pretty darn new! Patches super welcome.

Motivation

You deserve to get stuff done. You deserve a fast iteration loop. If you're writing TypeScript for node, you still deserve to have a fast interation loop. esbuild loves you, and I love you, and we think you deserve it.

This tool prioritizes rebooting a node.js TypeScript project as fast as possible. If you're writing a node server that requires a lot of code, or does heavy typechecking, running a TypeScript build every time you want to restart the server is too slow. Running a bunch of tools in a chain like tsc --watch and nodemon can be slow and suck up attention better spent on your actual work. This tool builds your project and then watches for changes on the filesystem (or terminal commands) to restart the process, and does everything it can to make that reload as fast as possible.

This means it doesn't typecheck. Type checking gets prohibitively slow at scale, so we recommend using a separate typechecker that still gives you the valuable feedback, but out of band so you don't have to wait for it to see if your change actually worked. We usually don't run anything other than VSCode's TypeScript integration locally, and then run a full tsc --noEmit in CI.

Because we don't want to typecheck, we can use esbuild for it's outrageously fast TypeScript to JavaScript compilation, and it's incremental mode for running only the minimal amount of rebuilding necessary each time you change the filesystem. Woop woop!

Usage

Options:
      --help       Show help                                           [boolean]
      --version    Show version number                                 [boolean]
  -c, --commands   Trigger commands by watching for them on stdin. Prevents
                   stdin from being forwarded to the process. Only command right
                   now is `rs` to restart the server. [boolean] [default: false]
  -w, --watch      Trigger restarts by watching for changes to required files
                                                       [boolean] [default: true]
  -s, --supervise  Supervise and restart the process when it exits indefinitely
                                                      [boolean] [default: false]

Comparison to `ts-node-dev`

ts-node-dev (and ts-node) accomplish a similar feat but are often 5-10x slower than esbuild-dev in big projects. They are loaded with features and will keep up with new TypeScript features much better as they use the mainline TypeScript compiler sources, and we think they make lots of sense! Because they use TypeScript proper for compilation though, even with --transpile-only, they are destined to be slower than esbuild. esbuild-devis for the times where you care a lot more about performance and are ok with the tradeoffs esbuild makes, like not supportingconst enum and being a touch behind on supporting new TypeScript releases.