Quick start

npm install --save keyv memoized-keyv

const memoize = require('memoized-keyv');

const memoizedRequest = memoize(request);

memoizedRequest('http://example.com').then(resp => { /* from request */ });
// later
memoizedRequest('http://example.com').then(resp => { /* from cache */ });

Usage

You can pass an options object, uri string, or keyv instance as second argument.

memoize(request, { store: new Map() });
memoize(request, 'redis://user:pass@localhost:6379');
memoize(request, new Keyv());

Resolver

By default the first argument of your function call is used as cache key. You can use a resolver if you want to change the key. The resolver is called with the same arguments as the function.

const sum = (n1, n2) => n1 + n2;
const memoized = memoize(sum, new Keyv(), {
  resolver: (n1, n2) => `${n1}+${n2}`
});

memoized(1, 2); // cached as { '1+2': 3 }

Note that memoized-keyv uses flood protection internally based on the result of this resolver. This means you can make as many requests as you want simultaneously while being sure you won't flood your async resource.

TTL

Set ttl to a number for a static TTL value.

const memoizedRequest = memoize(request, new Keyv(), { ttl: 60000 });

memoizedRequest('http://example.com'); // cached for 60 seconds

Set ttl to a function for a dynamic TTL value.

const memoizedRequest = memoize(request, new Keyv(), {
  ttl: (resp) => resp.statusCode === 200 ? 60000 : 0
});

memoizedRequest('http://example.com'); // cached for 60 seconds only if response was 200 OK

Stale

Set stale to any number of milliseconds.

If the ttl of a requested resource is below this staleness threshold we will still return the stale value but meanwhile asynchronously refresh the value.

const memoizedRequest = memoize(request, new Keyv(), { stale: 10000, ttl: 60000 });
memoizedRequest('http://example.com'); // cached for 60 seconds
// … 55 seconds later
// Our cache will expire in 5 seconds.
// This is below the staleness threshold of 10 seconds.
memoizedRequest('http://example.com'); // returns cached result + refresh cache

When the stale option is set we won't delete expired items either. The same logic as above applies.

API

memoize(func[, keyv[, options]]) :function

• func :function
• keyv :object|string
• options :object
• options.stale :number
• options.ttl :function|number
• options.resolver :function