Registry / storage / lru-cache-promise

lru-cache-promise

library1.0.9jsnpmunverified

lru-cache-promise (v1.0.9) is a thin wrapper around Isaac Z. Schlueter's lru-cache that adds promise-based async value fetching via a getAsync method. It uses Bluebird for promises and ensures that only one fetch request per key is in flight at a time, deduplicating concurrent calls. The package is stable with no recent releases and minimal maintenance. It differs from other caching libraries by being extremely lightweight and focused solely on adding promise support to lru-cache, without additional features like TTL or statistics.

storage devops

npm install lru-cache-promise

github ↗package ↗homepage ↗

INSTALL

IMPORT

SIG · LRU-CACHE-PROMISE

lru-cache-promise

storagejavascriptv1.0.9

harness data pending

Install & Compatibility

Where this runs

No compatibility data collected yet for this library.

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

default

✓ import createCache from 'lru-cache-promise';

✗ const { default } = require('lru-cache-promise');

The default export is a factory function that creates a cache instance. Import via default import syntax. In CommonJS, use require('lru-cache-promise')() – calling the result.

cache instance

✓ const cache = require('lru-cache-promise')();

✗ const cache = require('lru-cache-promise');

The module exports a factory function, not a pre-created cache instance. Always call the require result as a function.

getAsync

✓ cache.getAsync('key', fetchFn).then(console.log);

✗ cache.get('key');

getAsync returns a Bluebird promise. The synchronous get() from the underlying lru-cache is also available but returns the value directly (or undefined).

Shows how to use getAsync with a fetch function that returns a promise, including deduplication of concurrent requests.

import createCache from 'lru-cache-promise'; const cache = createCache({ max: 100 }); function fetchUser(id) { // Simulate async fetch return new Promise((resolve) => { setTimeout(() => resolve({ id, name: `User ${id}` }), 100); }); } cache.getAsync('user:1', fetchUser) .then(user => console.log(user)) .catch(err => console.error(err)); // Deduplication: multiple concurrent calls for same key Promise.all([ cache.getAsync('user:1', fetchUser), cache.getAsync('user:1', fetchUser) ]).then(([u1, u2]) => { console.log('Both resolve with same object:', u1 === u2); // true });

Debug

Known issues

gotchaThe factory function requires instantiation. Forgetting to call the function will result in an error like 'TypeError: cache.getAsync is not a function'.

fix

Call the require result as a function: require('lru-cache-promise')()

affects: all

deprecatedDepends on bluebird; not using native Promises. This may complicate debugging or Promise chain interop with native Promises.

fix

Use a library that returns native Promises or wrap the result in Promise.resolve() if needed.

affects: all

gotchaUnderlying lru-cache version 2.x uses deprecated Node.js APIs and may emit deprecation warnings in Node 12+.

fix

Consider upgrading to a cache library that supports lru-cache v6+, e.g., lru-cache-fp or lru-cache-async.

affects: >=4.0

breakingBluebird's Promise implementation is used; do not assume native Promises are used. .finally() may require Bluebird's version.

fix

Use .lastly() from Bluebird or convert with Promise.resolve(cache.getAsync(...)).

affects: all

Errors

Common errors & fixes

TypeError: cache.getAsync is not a function

The module exports a factory function. You forgot to call it.

fix

const cache = require('lru-cache-promise')();

ReferenceError: Promise is not defined

Bluebird is not loaded or the environment lacks a Promise implementation.

fix

Ensure bluebird is installed: npm install bluebird

TypeError: fetchFunction is not a function

getAsync expects a function as second argument.

fix

Pass a function that returns a value or a promise.

Upgrade

Version history

1.0.9latest on npm

Audit

Dependencies

lru-cacherequiredCore caching implementation; lru-cache-promise wraps lru-cache's synchronous API.

bluebirdrequiredPromise library used for getAsync; Bluebird's Promise is required for the promise behavior.

Agent activity

16 hits · last 30 days

node

OpenAI (training)

Resources

githubhttps://github.com/balihoo/lru-cache-promise ↗

packagelru-cache-promise ↗

homepagehttps://github.com/balihoo/lru-cache-promise#readme ↗