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 the value.

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.

Take a key (TAKE):

myCache.take( key )

get the cached value and remove the key from the cache.
Equivalent to calling get(key) + del(key).
Useful for implementing single use mechanism such as OTP, where once a value is read it will become obsolete.

myCache.set( "myKey", "myValue" )
myCache.has( "myKey" ) // returns true because the key is cached right now
value = myCache.take( "myKey" ) // value === "myValue"; this also deletes the key
myCache.has( "myKey" ) // returns false because the key has been deleted

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
        }
    */

Flush the stats (FLUSH STATS):

myCache.flushStats()

Flush the stats.

myCache.flushStats();
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 ...
});

flush_stats

Fired when the cache stats has been flushed.

myCache.on( "flush_stats", 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

Other projects

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.