dev.js

/**
 * Concurrently run our various dev tasks.
 *
 * Usage: node dev
 **/

const app = require('.')
 , chalk = require('chalk'), {bold} = chalk
 , {red, green, blue, cyan, yellow} = bold
 , dev = module.exports = () => run({
 server: task(app.package.scripts['start'], {color: blue}),
 build: task(app.package.scripts['build-watch'], {color: green}),
 lint: task(app.package.scripts['lint-watch'], {color: cyan}),
 test: task(app.package.scripts['test-watch'], {color: yellow})
 });

const taskEnvironment = (path=require('path')) => {
 const env = {};
 for (const key in process.env) {
 env[key] = process.env[key];
 }
 Object.assign(env, {
 NODE_ENV: 'development',
 PATH: [ path.join(app.root, 'node_modules', '.bin')
 , process.env.PATH ].join(path.delimiter)
 });
 return env;
};

function run(tasks) {
 Object.keys(tasks)
 .map(name => tasks[name](name));
}

function task(command, {
 spawn=require('child_process').spawn,
 path=require('path'),
 color
}={}) {
 return name => {
 const stdout = log({name, color}, process.stdout)
 , stderr = log({name, color, text: red}, process.stderr)
 , proc = spawn(command, {
 shell: true,
 stdio: 'pipe',
 env: taskEnvironment(),
 }).on('error', stderr)
 .on('exit', (code, signal) => {
 stderr(`Exited with code ${code}`);
 if (signal) stderr(`Exited with signal ${signal}`);
 });
 proc.stdout.on('data', stdout);
 proc.stderr.on('data', stderr);
 };
}

function log({
 name,
 ts=timestamp,
 color=none,
 text=none,
}, out=process.stdout) {
 return data => data.toString()
 // Strip out screen-clearing control sequences, which really
 // muck up the output.
 .replace('\u001b[2J', '')
 .replace('\u001b[1;3H', '')
 .split('\n')
 .forEach(line => out.write(`${color(`${ts()} ${name} \t⎹ `)}${text(line)}\n`));
}

const dateformat = require('dateformat');
function timestamp() {
 return dateformat('yyyy-mm-dd HH:MM:ss (Z)');
}

function none(x) { return x; }

if (module === require.main) { dev(); }