node-cache

What is node-cache?

The node-cache package is a simple caching library for Node.js that provides in-memory cache functionality. It allows for storing and retrieving data from a temporary cache, which can help improve the performance of applications by reducing the need to fetch or compute the same data multiple times.

What are node-cache's main functionalities?

Set and Get Cache Items

This feature allows you to store a value with a key in the cache for a specified duration (in milliseconds). You can then retrieve the value using the key.

{"set": "cache.set('myKey', 'myValue', 10000)", "get": "cache.get('myKey')"}

Delete Cache Items

This feature enables you to delete a specific item from the cache using its key.

{"del": "cache.del('myKey')"}

Check if a Key Exists

This feature allows you to check if a key exists in the cache without retrieving its value.

{"has": "cache.has('myKey')"}

Flush All Cache Data

This feature clears the entire cache, removing all stored key-value pairs.

{"flushAll": "cache.flushAll()"}

Get Cache Statistics

This feature provides statistics about the cache, such as the number of items stored, hits, misses, and keyspace information.

{"getStats": "cache.getStats()"}

Other packages similar to node-cache

memory-cache

memory-cache is another simple in-memory cache for Node.js. It is similar to node-cache but does not offer as many features, such as node-cache's TTL (time-to-live) for cache items.

lru-cache

lru-cache is an in-memory cache library that implements a least-recently-used cache eviction policy. Unlike node-cache, which allows setting a TTL for each item, lru-cache evicts the least recently used items once it reaches a predefined capacity.

redis

redis is a Node.js client for the Redis database, which can be used as an in-memory data structure store. It is more complex and feature-rich than node-cache, supporting various data structures and persistence to disk.

README

Simple and fast NodeJS internal caching.

A simple caching module that has set, get and delete methods and works a little bit like memcached. Keys can have a timeout (ttl) after which they expire and are deleted from the cache. All keys are stored in a single object so the practical limit is at around 1m keys.

BREAKING MAJOR RELEASE v5.x

The recent 5.x release:

• dropped support for node versions before 8.x!
• removed the callback-based api from all methods (you can re-enable them with the option enableLegacyCallbacks)

BREAKING MAJOR RELEASE v6.x UPCOMING

Although not breaking per definition, our typescript rewrite will change internal functions and their names. Please get in contact with us, if you are using some parts of node-cache's internal api so we can work something out!

Install

	npm install node-cache --save

Or just require the node_cache.js file to get the superclass

Examples:

Initialize (INIT):

const NodeCache = require( "node-cache" );
const myCache = new NodeCache();

Options

• stdTTL: (default: 0) the standard ttl as number in seconds for every generated cache element. 0 = unlimited
• checkperiod: (default: 600) The period in seconds, as a number, used for the automatic delete check interval. 0 = no periodic check.
• useClones: (default: true) en/disable cloning of variables. If true you'll get a copy of the cached variable. If false you'll save and get just the reference.
  Note:
  • true is recommended if you want simplicity, because it'll behave like a server-based cache (it caches copies of plain data).
  • false is recommended if you want to achieve performance or save mutable objects or other complex types with mutability involved and wanted, because it'll only store references of your data.
  • Here's a simple code example showing the different behavior
• deleteOnExpire: (default: true) whether variables will be deleted automatically when they expire. If true the variable will be deleted. If false the variable will remain. You are encouraged to handle the variable upon the event expired by yourself.
• enableLegacyCallbacks: (default: false) re-enables the usage of callbacks instead of sync functions. Adds an additional cb argument to each function which resolves to (err, result). will be removed in node-cache v6.x.
• maxKeys: (default: -1) specifies a maximum amount of keys that can be stored in the cache. If a new item is set and the cache is full, an error is thrown and the key will not be saved in the cache. -1 disables the key limit.

const NodeCache = require( "node-cache" );
const myCache = new NodeCache( { stdTTL: 100, checkperiod: 120 } );

Since 4.1.0: Key-validation: The keys can be given as either string or number, but are casted to a string internally anyway. All other types will throw an error.

Store a key (SET):

myCache.set( key, val, [ ttl ] )

Sets a key value pair. It is possible to define a ttl (in seconds). Returns true on success.

obj = { my: "Special", variable: 42 };

success = myCache.set( "myKey", obj, 10000 );
// true

Note: If the key expires based on it's ttl it will be deleted entirely from the internal data object.

Store multiple keys (MSET):

myCache.mset(Array<{key, val, ttl?}>)

Sets multiple key val pairs. It is possible to define a ttl (seconds). Returns true on success.

const obj = { my: "Special", variable: 42 };
const obj2 = { my: "other special", variable: 1337 };

const success = myCache.mset([
	{key: "myKey", val: obj, ttl: 10000},
	{key: "myKey2", val: obj2},
])

Retrieve a key (GET):

myCache.get( key )

Gets a saved value from the cache. Returns a undefined if not found or expired. If the value was found it returns an object with the key value pair.

value = myCache.get( "myKey" );
if ( value == undefined ){
	// handle miss!
}
// { my: "Special", variable: 42 }

Since 2.0.0:

The return format changed to a simple value and a ENOTFOUND error if not found *( as result instance of Error )

Since 2.1.0:

The return format changed to a simple value, but a due to discussion in #11 a miss shouldn't return an error. So after 2.1.0 a miss returns undefined.

Get multiple keys (MGET):

myCache.mget( [ key1, key2, ..., keyn ] )

Gets multiple saved values from the cache. Returns an empty object {} if not found or expired. If the value was found it returns an object with the key value pair.

value = myCache.mget( [ "myKeyA", "myKeyB" ] );
/*
	{
		"myKeyA": { my: "Special", variable: 123 },
		"myKeyB": { the: "Glory", answer: 42 }
	}
*/

Since 2.0.0:

The method for mget changed from .get( [ "a", "b" ] ) to .mget( [ "a", "b" ] )

Delete a key (DEL):

myCache.del( key )

Delete a key. Returns the number of deleted entries. A delete will never fail.

value = myCache.del( "A" );
// 1

Delete multiple keys (MDEL):

myCache.del( [ key1, key2, ..., keyn ] )

Delete multiple keys. Returns the number of deleted entries. A delete will never fail.

value = myCache.del( "A" );
// 1

value = myCache.del( [ "B", "C" ] );
// 2

value = myCache.del( [ "A", "B", "C", "D" ] );
// 1 - because A, B and C not exists

Change TTL (TTL):

myCache.ttl( key, ttl )

Redefine the ttl of a key. Returns true if the key has been found and changed. Otherwise returns false. If the ttl-argument isn't passed the default-TTL will be used.

The key will be deleted when passing in a ttl < 0.

myCache = new NodeCache( { stdTTL: 100 } )
changed = myCache.ttl( "existentKey", 100 )
// true

changed2 = myCache.ttl( "missingKey", 100 )
// false

changed3 = myCache.ttl( "existentKey" )
// true

Get TTL (getTTL):

myCache.getTtl( key )

Receive the ttl of a key. You will get:

• undefined if the key does not exist
• 0 if this key has no ttl
• a timestamp in ms representing the time at which the key will expire

myCache = new NodeCache( { stdTTL: 100 } )

// Date.now() = 1456000500000
myCache.set( "ttlKey", "MyExpireData" )
myCache.set( "noTtlKey", "NonExpireData", 0 )

ts = myCache.getTtl( "ttlKey" )
// ts wil be approximately 1456000600000

ts = myCache.getTtl( "ttlKey" )
// ts wil be approximately 1456000600000

ts = myCache.getTtl( "noTtlKey" )
// ts = 0

ts = myCache.getTtl( "unknownKey" )
// ts = undefined

List keys (KEYS)

myCache.keys()

Returns an array of all existing keys.

mykeys = myCache.keys();

console.log( mykeys );
// [ "all", "my", "keys", "foo", "bar" ]

Has key (HAS)

myCache.has( key )

Returns boolean indicating if the key is cached.

exists = myCache.has( 'myKey' );

console.log( exists );

Statistics (STATS):

myCache.getStats()

Returns the statistics.

myCache.getStats();
	/*
		{
			keys: 0,    // global key count
			hits: 0,    // global hit count
			misses: 0,  // global miss count
			ksize: 0,   // global key size count in approximately bytes
			vsize: 0    // global value size count in approximately bytes
		}
	*/

Flush all data (FLUSH):

myCache.flushAll()

Flush all data.

myCache.flushAll();
myCache.getStats();
	/*
		{
			keys: 0,    // global key count
			hits: 0,    // global hit count
			misses: 0,  // global miss count
			ksize: 0,   // global key size count in approximately bytes
			vsize: 0    // global value size count in approximately bytes
		}
	*/

Close the cache:

myCache.close()

This will clear the interval timeout which is set on check period option.

myCache.close();

Events

set

Fired when a key has been added or changed. You will get the key and the value as callback argument.

myCache.on( "set", function( key, value ){
	// ... do something ...
});

del

Fired when a key has been removed manually or due to expiry. You will get the key and the deleted value as callback arguments.

myCache.on( "del", function( key, value ){
	// ... do something ...
});

expired

Fired when a key expires. You will get the key and value as callback argument.

myCache.on( "expired", function( key, value ){
	// ... do something ...
});

flush

Fired when the cache has been flushed.

myCache.on( "flush", function(){
	// ... do something ...
});

Breaking changes

version 2.x

Due to the Issue #11 the return format of the .get() method has been changed!

Instead of returning an object with the key { "myKey": "myValue" } it returns the value itself "myValue".

version 3.x

Due to the Issue #30 and Issue #27 variables will now be cloned. This could break your code, because for some variable types ( e.g. Promise ) its not possible to clone them. You can disable the cloning by setting the option useClones: false. In this case it's compatible with version 2.x.

version 5.x

Callbacks are deprecated in this version. They are still useable when enabling the enableLegacyCallbacks option when initializing the cache. Callbacks will be completely removed in 6.x.

Compatibility

Node-Cache supports all node versions >= 8

Release History

Version	Date	Description
5.0.2	2019-11-17	Fixed bug where expired values were deleted even though deleteOnExpire was set to false. Thanks to fielding-wilson!
5.0.1	2019-10-31	Fixed bug where users could not set null values. Thanks to StefanoSega, jwest23 and marudor!
5.0.0	2019-10-23	Remove lodash dependency, add .has(key) and .mset([{key,val,ttl}]) methods to the cache. Thanks to Regev Brody for PR [#132] and Sujesh Thekkepatt for PR [#142]! Also thank you, to all other contributors that remain unnamed here!
4.2.1	2019-07-22	Upgrade lodash to version 4.17.15 to suppress messages about unrelated security vulnerability
4.2.0	2018-02-01	Add options.promiseValueSize for promise value. Thanks to Ryan Roemer for the pull [#84]; Added option deleteOnExpire; Added DefinitelyTyped Typescript definitions. Thanks to Ulf Seltmann for the pulls [#90] and [#92]; Thanks to Daniel Jin for the readme fix in pull [#93]; Optimized test and ci configs.
4.1.1	2016-12-21	fix internal check interval for node < 0.10.25, thats the default node for ubuntu 14.04. Thanks to Jimmy Hwang for the pull #78; added more docker tests
4.1.0	2016-09-23	Added tests for different key types; Added key validation (must be string or number); Fixed .del bug where trying to delete a number key resulted in no deletion at all.
4.0.0	2016-09-20	Updated tests to mocha; Fixed .ttl bug to not delete key on .ttl( key, 0 ). This is also relevant if stdTTL=0. This causes the breaking change to 4.0.0.
3.2.1	2016-03-21	Updated lodash to 4.x.; optimized grunt
3.2.0	2016-01-29	Added method getTtl to get the time when a key expires. See #49
3.1.0	2016-01-29	Added option errorOnMissing to throw/callback an error o a miss during a .get( "key" ). Thanks to David Godfrey for the pull #45. Added docker files and a script to run test on different node versions locally
3.0.1	2016-01-13	Added .unref() to the checkTimeout so until node 0.10 it's not necessary to call .close() when your script is done. Thanks to Doug Moscrop for the pull #44.
3.0.0	2015-05-29	Return a cloned version of the cached element and save a cloned version of a variable. This can be disabled by setting the option useClones:false. (Thanks for #27 to cheshirecatalyst and for #30 to Matthieu Sieben)
2.2.0	2015-05-27	REVOKED VERSION, because of conficts. See Issue #30. So 2.2.0 is now 3.0.0
2.1.1	2015-04-17	Passed old value to the del event. Thanks to Qix for the pull.
2.1.0	2015-04-17	Changed get miss to return undefined instead of an error. Thanks to all #11 contributors
2.0.1	2015-04-17	Added close function (Thanks to ownagedj). Changed the development environment to use grunt.
2.0.0	2015-01-05	changed return format of .get() with a error return on a miss and added the .mget() method. Side effect: Performance of .get() up to 330 times faster!
1.1.0	2015-01-05	added .keys() method to list all existing keys
1.0.3	2014-11-07	fix for setting numeric values. Thanks to kaspars + optimized key ckeck.
1.0.2	2014-09-17	Small change for better ttl handling
1.0.1	2014-05-22	Readme typos. Thanks to mjschranz
1.0.0	2014-04-09	Made callbacks optional. So it's now possible to use a syncron syntax. The old syntax should also work well. Push : Bugfix for the value 0
0.4.1	2013-10-02	Added the value to expired event
0.4.0	2013-10-02	Added nodecache events
0.3.2	2012-05-31	Added Travis tests

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The MIT License (MIT)

Copyright © 2019 Mathias Peter and the node-cache maintainers, https://github.com/node-cache/node-cache

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.