react-component-isolator/run.js

A simple module that spins up a react app where the only component is the react component you pass in.

const { spawn } = require('child_process');

/**
 * Function that starts a command in another thread
 * @param {object} opts - all arguments for this function
 * @param {string} opts.command - the command to run
 * @param {string[]} opts.args - the args of the command to run
 * @param {string} [opts.cwd] - the current working directory to run the command
 *   in
 * @param {object} [opts.env] - the environment
 * @param {object} [opts.handlers] - a set of handlers
 * @param {function} [opts.handlers.onStdout] - a function to call with new
 *   stdout text
 * @param {function} [opts.handlers.onClose] - a function to call when the
 *   command is done executing (called with exit code)
 * @return {function} kill function (call this to kill the child process)
 */
module.exports = (opts) => {
  const { command } = opts;
  const args = opts.args || [];
  const env = opts.env || {};
  const handlers = opts.handlers || {};

  // Add path to environment
  env.PATH = process.env.PATH;

  // Start the process
  const child = spawn(command, args, {
    env,
    cwd: opts.cwd || process.cwd(),
  });

  // Watch for standard out
  child.stdout.setEncoding('utf8');
  child.stdout.on('data', (chunk) => {
    if (handlers.onStdout) {
      handlers.onStdout(chunk);
    }
  });

  // Watch for standard err
  child.stderr.setEncoding('utf8');
  child.stderr.on('data', (chunk) => {
    if (handlers.onStderr) {
      handlers.onStderr(chunk);
    }
  });

  // Watch for close
  child.on('close', (code) => {
    if (handlers.onClose) {
      handlers.onClose(code);
    }
  });

  return () => {
    child.kill();
  };
};