lruj

lruj is a simple Least Recently Used cache implementation in javascript, using a doubly linked list.

API

• set(key, value) : set a value in the cache or update an existing one (and mark it as "used", i.e. move it to the top)
• get(key, [getDataFn]) : get a value from the cache and move it to the top, returns undefined if not found. getDataFn is an optional convenient function that is called when caches misses, the returned value of getDataFn will be set in the cache at the key provided.

Usage

// Number of items that will be stored in the cache
const maxSize = 100;
var cache = new LRU(maxSize);

cache.set(1, "value 1");
cache.get(1)
=> 'value 1'

cache.get(99)
=> undefined

// Get items from the cache with a convenient function to set the value when cache entry is missing
cache.get(99, () => {
  console.log('fetching data 99');
  // HTTP.get('https://my-api.dev/99')
  return 'data 99';
});
fetching data 99
=> 'data 99'

// The second time the function is called, it will hit the cache and not execute the function passed as a parameter
cache.get(99, () => { 
  console.log('fetching data 99'); 
  // HTTP.get('https://my-api.dev/99') 
  return 'Modified data 99'; 
});
=> 'data 99'

Development

Download the repository:

git clone [email protected]:jazzytomato/lruj.git

Install dependencies:

cd lruj
npm install

Run tests with npm test