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. |
| --noColors | By default tsc-watch adds colors the output with green
on success, and in red on failure.
Add this argument to prevent that. |
| --noWatch | By default tsc-watch adds --watch. using this to prevent watch. |
| --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. |
| --maxNodeMem | Calls node with a specific memory limit max_old_space_size, to use if your project needs more memory. |
| --compiler PATH | [Deprecated] The PATH will be used instead of typescript compiler.
Default is typescript/bin/tsc |
| --compileCommand COMMAND | The COMMAND will be used to execute the typescript compiler. Replaces --compiler PATH and --maxNodeMem |

Notes:

- 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.

- To prevent the watch, use --noWatch or pass --watch false as a parameter.

- tsc-watch supports tsgo (native compilation), just select the compiler path. tsc-watch --compileCommand tsgo or tsc-watch --compileCommand "yarn tsgo"

$3

#### Run your server after successful project compilation
``json
"scripts": {
"dev": "tsc-watch -b ./src/tsconfig.json --onSuccess \"yarn start-dev-server\""
}
`

#### Using tsgo (native compilation)
`json
"scripts": {
"dev": "tsc-watch --compileCommand tsgo"
}
`

Install

`sh
npm install tsc-watch --save-dev
`

`sh

for command-line usage

npm install -g typescript tsc-watch
`

Usage

$3

`sh

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
`

$3

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

$3

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:

`javascript
// 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.
}
`

Notes:

- 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.
- if tsc-watch was installed globally, it will use the local compiler if it exists, otherwise it will use the global tsc` compiler.