// app.jsvar pack = require('./pack/abc');var pack1 = require('./pack1');var pack2 = require('./pack2');pack.info();pack1.info();pack2.info();

// pack/abc.jsexports.info = function () {    console.log('module');}

// pack1/index.jsexports.info = function () {    console.log('pack1');}

// pack2/abc.jsexports.info = function () {    console.log('pack2');}

// pack2/package.json{    "main": "./abc.js"}