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6.2.0 • Public • Published

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The nodemon for TypeScript

tsc-watch starts the installed TypeScript compiler (tsc) with --watch parameter, with the ability to react to compilation status. tsc-watch was created to allow an easy dev process with TypeScript. Commonly used to restart a node server, similar to nodemon but for TypeScript.

Anything that you can do with tsc you can do with tsc-watch, the only difference is that tsc-watch can react to compilation status.

Argument Description
--onSuccess COMMAND Executes COMMAND on every successful compilation.
--onFirstSuccess COMMAND Executes COMMAND on the first successful compilation.
--onEmit COMMAND Executes debounced COMMAND on every emitted file, ignoring unchanged files and disregards compilation success or failure.
--onEmitDebounceMs DELAY Delay by which to debounce --onEmit (default: 300).
--onFailure COMMAND Executes COMMAND on every failed compilation.
--onCompilationStarted COMMAND Executes COMMAND on every compilation start event (initial and incremental).
--onCompilationComplete COMMAND Executes COMMAND on every successful or failed compilation.
--maxNodeMem Calls node with a specific memory limit max_old_space_size, to use if your project needs more memory.
--noColors By default tsc-watch adds colors the output with green
on success, and in red on failure.
Add this argument to prevent that.
--noClear In watch mode the tsc compiler clears the screen before reporting
Add this argument to prevent that.
--signalEmittedFiles Will run tsc compiler with --listEmittedFiles, but hiding TSFILE lines. Use it to enable file_emitted event, while keeping tsc stdout silent.
--silent Do not print any messages on stdout.
--compiler PATH The PATH will be used instead of typescript compiler.
Default is typescript/bin/tsc


  • That all the above COMMANDs will be killed on process exit. (Using SIGTERM)

  • A COMMAND is a single command and not multi command like script1.sh && script2.sh

  • Any child process (COMMAND) will be terminated before creating a new one.


npm install tsc-watch --save-dev
## for command-line usage
npm install -g typescript tsc-watch


From Command-Line

## Watching a project (with tsconfig.json)
tsc-watch --onSuccess "node ./dist/server.js"

## Beep on failure
tsc-watch --onFailure "echo Beep! Compilation Failed"

## Watching a single file
tsc-watch server.ts --outDir ./dist --onSuccess "node ./dist/server.js"

## Custom compiler
tsc-watch --onSuccess "node ./dist/server.js" --compiler my-typescript/bin/tsc

From npm script

"dev-server": "tsc-watch --noClear -p ./src/tsconfig.json --onSuccess \"node ./dist/server.js\"",

From javascript

You can see a detailed example here

The client is implemented as an instance of Node.JS's EventEmitter, with the following events:

  • started - Emitted upon the compilation start (initial or incremental).
  • first_success - Emitted upon first successful compilation.
  • subsequent_success - Emitted upon every subsequent successful compilation.
  • compile_errors - Emitted upon every failing compilation.
  • file_emitted - Emitted upon every file transpiled if --listEmittedFiles is used.

Once subscribed to the relevant events, start the client by running watch.start()

To kill the client, run watch.kill()

Example usage:

// Using CommonJS:
const { TscWatchClient } = require('tsc-watch/client');
// Using ES6 import:
import { TscWatchClient } from 'tsc-watch/client';

const watch = new TscWatchClient();

watch.on('started', () => {
  console.log('Compilation started');

watch.on('first_success', () => {
  console.log('First success!');

watch.on('success', () => {
  // Your code goes here...

watch.on('compile_errors', () => {
  // Your code goes here...

watch.start('--project', '.');

try {
  // do something...
} catch (e) {
  watch.kill(); // Fatal error, kill the compiler instance.


  • The (onSuccess) COMMAND will not run if the compilation failed.
  • The (onEmit) COMMAND will not run if the compilation succeeded with no changed files, unless it is the first success.
  • The (onEmit) COMMAND will run even if the compilation failed, but emitted changed files.
  • The (onEmit) COMMAND will not run 100 times for 100 files, due to --onEmitDebounce
  • The (onEmit) COMMAND is not cancelling the onSuccess/onFirstSuccess/onFailure/onCompilationComplete/onCompilationStarted commands and vice versa.
  • tsc-watch is using the currently installed TypeScript compiler.
  • tsc-watch is not changing the compiler, just adds the new arguments, compilation is the same, and all other arguments are the same.



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npm i tsc-watch

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  • gilamran