Least Recently Used (LRU) Cache with Node.js Map 🗺️

A straightforward Least Recently Used (LRU) cache implementation using the native Map object in Node.js. Bundled with Polka HTTP server for easy access.

Getting Started

git clone https://github.com/cgatno/least-recently-used.git
cd least-recently-used
npm install
npm start

See the HTTP interface specs below for info on using the cache.

Features

This LRU caching app implements the following functionality:

• Finite and hold up to a maximum number of elements
• Supports ‘get,’ ‘put,’ and ‘delete' operations
• Discards the least recently used elements first
• Accessible using HTTP

Using the Cache

You can access the cache using any HTTP client (or web browser for GET requests). I recommend Postman or httpie.

See below for a list of app endpoints.

HTTP Interface

By default, the app listens at http://localhost:8080. The port can be overriden using the PORT environment variable. (E.g. PORT=4343 npm start)

Endpoint	Request Type	Input (application/json)	Response Code	Response Description
/	GET	N/A	200	Friendly, descriptive welcome message 😊
/cache	GET	N/A	200	JSON array of form [<key>, <value>] for most recently used pair
	POST	{key: string?, value: string?}	200	JSON array of form [<new key>, <new value>]
			500	Add pair error message - stack trace logged to Node console
/cache/{key}	GET	N/A	200	Plaintext value for the given key
			404	Key not found message
	DELETE	N/A	200	Key deleted message
			404	Key not found message
	PUT	{value: string?}	200	JSON array of form [<key>, <new value>]
			500	Key update error message - stack trace logged to Node console

Roadmap (TODO)

• Outfit toolchain with nodemon to automatically reload in dev environment
• Test performance of JavaScript Map to see if more performant implementation is necessary
• Build UI for interacting with the Express API and underlying cache
• Add persist/load functions to LRU cache
• Promisify LRUCache.js for async operations