callback-queue

A Node.js library for queuing callbacks so that concurrent requests for the same resource are executed only once. Current stable version is 3.0.0. It allows you to deduplicate simultaneous calls to the same function (e.g., HTTP requests) by queuing callbacks under a key. Once the first call completes, all queued callbacks receive the result. Works in Node.js and browser via browserify. Lightweight and simple, with no external dependencies.