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

node-cache

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 after which they expire and are cleaned from the cache.
All keys are stored in a single object so the practical limit is at around 1m keys.

Install

  npm install node-cache

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

Examples:

Initialize (INIT):

var NodeCache = require( "node-cache" );
var 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.
  Note: If you use checkperiod > 0 you script will not exit at the end, because a internal timeout will allways be active.

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

Store a key (SET):

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

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

obj = { my: "Special", variable: 42 };
myCache.set( "myKey", obj, function( err, success ){
  if( !err && success ){
    console.log( success );
    // true
    // ... do something ...
  }
});

Since 1.0.0:
Callback is now optional. You can also use synchronous syntax.

obj = { my: "Special", variable: 42 };
success = myCache.set( "myKey", obj, 10000 );
// true

Retrieve a key (GET):

myCache.get( key, [callback] )

Gets a saved value 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.

myCache.get( "myKey", function( err, value ){
  if( !err ){
    console.log( value );
    // { "myKey": { my: "Special", variable: 42 } }
    // ... do something ...
  }
});

Since 1.0.0:
Callback is now optional. You can also use synchronous syntax.

value = myCache.get( "myKey" );
// { "myKey": { my: "Special", variable: 42 } }

Get multiple keys (MGET):

myCache.get( [ key1, key2, ... ,keyn ], [callback] )

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.

myCache.get( [ "myKeyA", "myKeyB" ], function( err, value ){
  if( !err ){
    console.log( value );
    /*
      {
        "myKeyA": { my: "Special", variable: 123 },
        "myKeyB": { the: "Glory", answer: 42 }
      }
    */
    // ... do something ...
  }
});

Since 1.0.0:
Callback is now optional. You can also use synchronous syntax.

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

Delete a key (DEL):

myCache.del( key, [callback] )

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

myCache.del( "myKey", function( err, count ){
  if( !err ){
    console.log( count ); // 1
    // ... do something ...
  }
});

Since 1.0.0:
Callback is now optional. You can also use synchronous syntax.

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

Delete multiple keys (MDEL):

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

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

myCache.del( [ "myKeyA", "myKeyB" ], function( err, count ){
  if( !err ){
    console.log( count ); // 2
    // ... do something ...
  }
});

Since 1.0.0:
Callback is now optional. You can also use synchronous syntax.

value = myCache.del( [ "myKeyA", "myKeyB", "notExistendKey" ] );
// 2

Change TTL (TTL):

myCache.ttl( key, ttl, [callback] )

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.

myCache = new NodeCache( { stdTTL: 100 } )
myCache.ttl( "existendKey", 100, function( err, changed ){
  if( !err ){
    console.log( changed ); // true
    // ... do something ...
  }
});

myCache.ttl( "missingKey", 100, function( err, changed ){
  if( !err ){
    console.log( changed ); // false
    // ... do something ...
  }
});

myCache.ttl( "existendKey", function( err, changed ){
  if( !err ){
    console.log( changed ); // true
    // ... do something ...
  }
});

Since 1.0.0:
Callback is now optional. You can also use synchronous syntax.

value = myCache.ttl( "existendKey", 100 );
// true

List keys (KEYS)

myCache.keys( [callback] )

Returns an array of all existing keys.

// async
myCache.keys( function( err, mykeys ){
  if( !err ){
    console.log( mykeys );
   // [ "all", "my", "keys", "foo", "bar" ]
  }
});

// sync
mykeys = myCache.keys();

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

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
      vsize: 0    // global value size count
    }
  */

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
      vsize: 0    // global value size count
    }
  */

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 as callback argument.

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

Release History

Version	Date	Description
v1.1.0	2014-11-07	added .keys method to list all existing keys
v1.0.3	2014-11-07	fix for setting numeric values. Thanks to kaspars + optimized key ckeck.
v1.0.2	2014-09-17	Small change for better ttl handling
v1.0.1	2014-05-22	Readme typos. Thanks to mjschranz
v1.0.0	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
v0.4.1	2013-10-02	Added the value to expired event
v0.4.0	2013-10-02	Added nodecache events
v0.3.2	2012-05-31	Added Travis tests

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The MIT License (MIT)

Copyright © 2013 Mathias Peter, http://www.tcs.de

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.