Node module caching

counter.js

var count = 0;
count++;
module.exports = count;

dep1.js

require('./counter') // => 1

dep2.js

require('./counter') // => 1

runner.js

// count reference does not exist yet

// resolve and initialize the counter module
// it creates a counter reference as 0, increments it, and exports it
require('./counter');

// retrieve the cached counter module
// count reference is unchanged because counter is not re-evaluated
require('./dep1');
require('./dep2');