Introduction to Cross-Spawn

Cross-Spawn is a versatile library for spawning child processes in a way that works consistently across platforms. It provides a range of APIs making it easier to handle cwd, env, and more.

Getting Started

First, you will need to install cross-spawn in your project:

  npm install cross-spawn

API Examples

Basic Usage

The basic syntax requires the command you wish to run as the first argument:

  const spawn = require('cross-spawn');
  const result = spawn.sync('echo', ['Hello, World!']);
  console.log(result.stdout.toString()); // Hello, World!

Async Usage

Using cross-spawn asynchronously:

  const spawn = require('cross-spawn');
  const process = spawn('node', ['-v']);
  
  process.stdout.on('data', (data) => {
    console.log(data.toString());
  });

Handling Errors

Handling errors when spawning processes:

  const spawn = require('cross-spawn');
  const result = spawn.sync('invalid-command');
  
  if (result.error) {
    console.error(result.error);
  }

Setting Environment Variables

Using custom environment variables:

  const spawn = require('cross-spawn');
  const result = spawn.sync('node', ['-e', 'console.log(process.env.TEST_ENV)'], {
    env: {TEST_ENV: 'CustomVar'}
  });
  console.log(result.stdout.toString()); // CustomVar

Real World Example

Here’s a complete example of building a simple app that compiles a TypeScript project, logs the output, and handles errors efficiently:

  const spawn = require('cross-spawn');

  function compileProject() {
    const compileProcess = spawn('tsc', ['-p', '.']);
    
    compileProcess.stdout.on('data', (data) => {
      console.log(`stdout: ${data}`);
    });

    compileProcess.stderr.on('data', (data) => {
      console.error(`stderr: ${data}`);
    });

    compileProcess.on('close', (code) => {
      console.log(`child process exited with code ${code}`);
    });

    compileProcess.on('error', (err) => {
      console.error(`Failed to start subprocess: ${err}`);
    });
  }

  compileProject();

By using cross-spawn, developers can create more reliable and consistent Node.js applications that work across different operating systems.

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