Simple, cross-platform way to open the browser upon starting an app.

open.js

const cp = require('child_process');
const Koa = require('koa');
const app = new Koa();
const cmds = { linux: 'xdg-open', win32: 'start chrome', darwin: 'open' };
const open = cmds[process.platform];
const PORT = 3000;

// response
app.use(ctx => {
  ctx.body = 'Hello Koa';
});

cp.execSync(`${open} http://localhost:${PORT}/`);
app.listen(PORT);