Run Nodemon with Typescript compiling?

Question

I want my typescript files to be compiled on every file saving with the command tsc.

How do I combine the tsc command with the command that nodemon runs in the build:live script

"scripts": {
    "start": "npm run build:live",
    "build:live": "nodemon --watch '*.ts' --exec 'ts-node' app.ts",
 }

this script causes nodemon to call itself twice or three times:

"build:live": "nodemon --watch '*.ts' --exec 'ts-node app.ts & tsc'",

Precipitate

Answer 1

This looks like it will achieve what you're looking for:

"start": "tsc-watch --project . --outDir ./dist --onSuccess \"nodemon ./dist/bin/www.js\""

Source: https://github.com/Microsoft/TypeScript/issues/12996#issuecomment-349277673

Zootoxin

This solved my exact problem. I wanted the TS to transpile, make sure the transpilation was successful and then run a specific file in dist. Thank you! – Tertullian

Answer 2

Nodemon will detect and run .ts files with ts-node automatically now. It will actually run .py and .rb files with python and ruby too btw and you can give it a custom --exec for others. Here's a link to the relevant code within nodemon.

So the following should be fine:

"scripts": {
  "dev": "nodemon app.ts"
}

Diastase

Answer 3

With the current answer you might run into issues using ES modules. No need for nodemon when you're using tsc-watch. It makes use of incremental compilation, making the restart of your application much faster.

I found the following to work best:

"start": "tsc-watch --onSuccess \"node ./dist/app.js\""

The outDir can be defined in your tsconfig

Shlomo

Answer 4

As of TypeScript 3.8+, you can now just use:

tsc --watch

https://www.typescriptlang.org/docs/handbook/configuring-watch.html

You could then use nodemon on the compiled code, e.g. nodemon dist/app.js.

Arquebus

this is the correct answer! thank you. – Indeterminacy

Answer 5

You can create a nodemon.json in your project root directory and add the following code inside that:

{
 "ext": "*.ts",
 "exec": "tsc && ts-node app.ts"
}

And update your scripts like following:

"scripts": {
   "start": "npm run build:live",
   "build:live": "nodemon",
}

What happens is that nodemon will check all the files with the extension ".ts" and starts tsc and then ts-node.

Oenone

Answer 6

I'm using nodemon + concurrently libraries:

"watch": "concurrently \"npm run build -- --watch\" \"nodemon --watch '**/*' --exec npm run start\"",

build script:

"build": "tsc"

Namara