@types/lru-cache

constructor

constructor(options?: LRUCache.Options<K, V>);

constructor

constructor(max: number);

property allowStale

allowStale: boolean;

• Same as Options.allowStale.

property itemCount

readonly itemCount: number;

• Return total quantity of objects currently in cache. Note, that stale (see options) items are returned as part of this item count.

property length

readonly length: number;

• Return total length of objects in cache taking into account length options function.

property max

max: number;

• Same as Options.max. Resizes the cache when the max changes.

property maxAge

maxAge: number;

• Same as Options.maxAge. Resizes the cache when the maxAge changes.

method del

del: (key: K) => void;

• Deletes a key out of the cache.

method dump

dump: () => Array<LRUCache.Entry<K, V>>;

• Return an array of the cache entries ready for serialization and usage with destinationCache.load(arr).

method forEach

forEach: <T = this>(
    callbackFn: (this: T, value: V, key: K, cache: this) => void,
    thisArg?: T
) => void;

• Just like Array.prototype.forEach. Iterates over all the keys in the cache, in order of recent-ness. (Ie, more recently used items are iterated over first.)

method get

get: (key: K) => V | undefined;

• Will update the "recently used"-ness of the key. They do what you think. maxAge is optional and overrides the cache maxAge option if provided.

  If the key is not found, will return undefined.

method has

has: (key: K) => boolean;

• Check if a key is in the cache, without updating the recent-ness or deleting it for being stale.

method keys

keys: () => K[];

• Return an array of the keys in the cache.

method lengthCalculator

lengthCalculator: (value: V) => number;

• Same as Options.length.

method load

load: (cacheEntries: ReadonlyArray<LRUCache.Entry<K, V>>) => void;

• Loads another cache entries array, obtained with sourceCache.dump(), into the cache. The destination cache is reset before loading new entries

  Parameter cacheEntries

  Obtained from sourceCache.dump()

method peek

peek: (key: K) => V | undefined;

• Returns the key value (or undefined if not found) without updating the "recently used"-ness of the key.

  (If you find yourself using this a lot, you might be using the wrong sort of data structure, but there are some use cases where it's handy.)

method prune

prune: () => void;

• Manually iterates over the entire cache proactively pruning old entries.

method reset

reset: () => void;

• Clear the cache entirely, throwing away all values.

method rforEach

rforEach: <T = this>(
    callbackFn: (this: T, value: V, key: K, cache: this) => void,
    thisArg?: T
) => void;

• The same as cache.forEach(...) but items are iterated over in reverse order. (ie, less recently used items are iterated over first.)

method set

set: (key: K, value: V, maxAge?: number) => boolean;

• Will update the "recently used"-ness of the key. They do what you think. maxAge is optional and overrides the cache maxAge option if provided.

method values

values: () => V[];

• Return an array of the values in the cache.

property e

e: number;

property k

k: K;

property v

v: V;

property max

max?: number | undefined;

• The maximum size of the cache, checked by applying the length function to all values in the cache. Not setting this is kind of silly, since that's the whole purpose of this lib, but it defaults to Infinity.

property maxAge

maxAge?: number | undefined;

• Maximum age in ms. Items are not pro-actively pruned out as they age, but if you try to get an item that is too old, it'll drop it and return undefined instead of giving it to you.

property noDisposeOnSet

noDisposeOnSet?: boolean | undefined;

• By default, if you set a dispose() method, then it'll be called whenever a set() operation overwrites an existing key. If you set this option, dispose() will only be called when a key falls out of the cache, not when it is overwritten.

property stale

stale?: boolean | undefined;

• By default, if you set a maxAge, it'll only actually pull stale items out of the cache when you get(key). (That is, it's not pre-emptively doing a setTimeout or anything.) If you set stale:true, it'll return the stale value before deleting it. If you don't set this, then it'll return undefined when you try to get a stale entry, as if it had already been deleted.

property updateAgeOnGet

updateAgeOnGet?: boolean | undefined;

• When using time-expiring entries with maxAge, setting this to true will make each item's effective time update to the current time whenever it is retrieved from cache, causing it to not expire. (It can still fall out of cache based on recency of use, of course.)

method dispose

dispose: (key: K, value: V) => void;

• Function that is called on items when they are dropped from the cache. This can be handy if you want to close file descriptors or do other cleanup tasks when items are no longer accessible. Called with key, value. It's called before actually removing the item from the internal cache, so if you want to immediately put it back in, you'll have to do that in a nextTick or setTimeout callback or it won't do anything.

method length

length: (value: V, key?: K) => number;

• Function that is used to calculate the length of stored items. If you're storing strings or buffers, then you probably want to do something like function(n, key){return n.length}. The default is function(){return 1}, which is fine if you want to store max like-sized things. The item is passed as the first argument, and the key is passed as the second argument.