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    0.1.4 • Public • Published

    LRU Memorise Fn

    A simple memorise function that uses a fast LRU cache under the hood.

    Basic features

    • Works in Node and the browser
    • Memorises both sync and async functions.
    • Automatic cache key generation from function arguments
    • Cache TTL / value expiry
    • Fully typed: memorised functions inherit their source function types.
    • Bring your own cache or cache-keygen function, or we create one for you.
    • Cache is exposed for the memorised function, if you want to access it and modify or manually clear.


    import memorise from "lru-memorise";
    const answerMyToughQuestion = (question: string) => {
      // ... heavy compute
      return response;
    const memorisedFn = memorise(answerMyToughQuestion);
    memorisedFn(`What's the meaning of life?`); // Calls source fn, response cached #1.
    memorisedFn(`Are you an AI?`); // Calls source fn, response cached #2.
    memorisedFn(`What's the meaning of life?`); // Returns cached value #1
    memorisedFn(`Are you an AI?`); // Returns cached value #2


    Note, all options are optional

    Option Default Description
    cache undefined Bring your own LRU cache, as long as it supports standard set and get operations
    cacheKeyResolver defaultFn Function used to generate unique cache key from arguments. Takes array of arguments, and return a string.
    lruOptions { max: 1000 } Default options for tiny-lru. The two options are max and ttl.

    Bring your own cache

    Under the hood we use tiny-lru, but you can bring your own, or create your cache outside and use it.

    If you don't provide one, we create a cache for you. This cache is exposed through the _cache function, if you want to have access to it.

    Bring your own cache key resolver

    We have a simple function to generate a cache key from function arguments, using JSON.stringify. You can of course pass your own custom one if you have a more complex situation, or want to cache to behave differently. It should return a string.

    type Resolver = (...args: any[]) => string;

    Tiny-LRU Options

    By default, we limit the max cache size to 1000 keys, and we don't set a TTL on the key values.

    Type LRUOPtions = {
      max: number // Max number of keys in Cache
      ttl: number // Expiry of items in cache


    npm i lru-memorise

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    • chrisajames