How to watch and reload ts-node when TypeScript files change

You can now simply npm install --save-dev ts-node nodemon and then run nodemon with a .ts file and it will Just Work:

nodemon app.ts

Previous versions:

I was struggling with the same thing for my development environment until I noticed that nodemon's API allows us to change its default behaviour in order to execute a custom command.

For example, for the most recent version of nodemon:

nodemon --watch "src/**" --ext "ts,json" --ignore "src/**/*.spec.ts" --exec "ts-node src/index.ts"

Or create a nodemon.json file with the following content:

{
  "watch": ["src"],
  "ext": "ts,json",
  "ignore": ["src/**/*.spec.ts"],
  "exec": "ts-node ./src/index.ts"      // or "npx ts-node src/index.ts"
}

and then run nodemon with no arguments.

By virtue of doing this, you'll be able to live-reload a ts-node process without having to worry about the underlying implementation.

Cheers!

And with even older versions of nodemon:

nodemon --watch 'src/**/*.ts' --ignore 'src/**/*.spec.ts' --exec 'ts-node' src/index.ts

Or even better: externalize nodemon's config to a nodemon.json file with the following content, and then just run nodemon, as Sandokan suggested:

{
  "watch": ["src/**/*.ts"],
  "ignore": ["src/**/*.spec.ts"],
  "exec": "ts-node ./index.ts"
}

I've dumped nodemon and ts-node in favor of a much better alternative, ts-node-dev https://github.com/whitecolor/ts-node-dev

Just run ts-node-dev src/index.ts

Here's an alternative to the HeberLZ's answer, using npm scripts.

My package.json:

  "scripts": {
    "watch": "nodemon -e ts -w ./src -x npm run watch:serve",
    "watch:serve": "ts-node --inspect src/index.ts"
  },

• -e flag sets the extenstions to look for,
• -w sets the watched directory,
• -x executes the script.

--inspect in the watch:serve script is actually a node.js flag, it just enables debugging protocol.

This works for me:

nodemon src/index.ts

Apparently thanks to since this pull request: https://github.com/remy/nodemon/pull/1552

Specifically for this issue I've created the tsc-watch library. you can find it on npm.

Obvious use case would be:

tsc-watch server.ts --outDir ./dist --onSuccess "node ./dist/server.js"