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The TypeScript compiler with --watch and a new onSuccess argument
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The TypeScript compiler with --onSuccess argument

tsc-watch starts a TypeScript compiler with --watch parameter, there are 5 new arguments.

  • --onSuccess COMMAND - The COMMAND will be executed on every successful TypeScript compilation. The process will be killed and restarted on every successful compilation.
  • --onFirstSuccess COMMAND - The COMMAND will be executed only one time, on the first successful TypeScript compilation, it will not get killed on every success.
  • --onFailure COMMAND - The COMMAND will be executed on failed TypeScript compilation.
  • --noColors - tsc-watch colors the output with green on success, and in red on failiure. Add this argument to prevent that.
  • --noClear - In watch mode the tsc compiler clears the screen before reporting, using this option will prevent that.
  • --compiler PATH - The PATH will be used instead of typescript compiler. Defaults typescript/bin/tsc.

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

Install

npm install tsc-watch --save-dev

Usage

From Command-Line

## Compiles the server.ts into the dist folder and run it
tsc-watch server.ts --outDir ./dist --onSuccess "node ./dist/server.js" --onFailure "echo Beep! Compilation Failed" --compiler typescript/bin/tsc

## With tsconfig.json
tsc-watch --onSuccess "node ./dist/server.js" --onFailure "echo Beep! Compilation Failed" --compiler typescript/bin/tsc

From Code

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

  • first_success - Emitted upon first successful compilation.
  • subsequent_success - Emitted upon every subsequent successful compilation.
  • compile_errors - Emitted upon every failing compilation.

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

To kill the client, run watch.kill()

Example usage:

const TscWatchClient = require('tsc-watch/client');
const watch = new TscWatchClient();

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.
  • Any child process (COMMAND) will be terminated before creating a new one.
  • 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.
  • tsc-watch was created to allow an easy dev process with TypeScript. Commonly used to restart a node server.
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