node-persist - localStorage on the server

Super-easy asynchronous persistent data structures in Node.js, modeled after HTML5 localStorage

Node-persist doesn't use a database. Instead, JSON documents are stored in the file system for persistence. Because there is no network overhead, node-persist is just about as fast as a database can get. Node-persist uses the HTML5 localStorage API, so it's easy to learn.

This is still a work in progress. Send pull requests please.

Note

• This is not designed for large amounts of data, you can do way more than the 5MB limit imposed by the browsers but don't stretch it, in some cases you might need to load the whole storage into RAM, but normat getItem/setItem does not.
• If you're looking for the version that supports both synchronous and asynchronous use node-persist@2.1.0

Table of Contents

Install

Example

Change Logs

API

Install

1$ npm install node-persist

Basic Example

1const storage = require('node-persist');
2
3//you must first call storage.init or initSync
4storage.initSync( /* options ... */ );
5// or 
6// storage.init( /* options ... */ );
7
8// then anywhere else in your code
9await storage.setItem('name','yourname')
10console.log(await storage.getItem('name')); // yourname

Run the counter example:

1$ cd examples/counter
2$ node counter.js
3$ open up localhost:8080

Change Logs

4.0.0

Non-backward changes

• Switch file hashes from md5 to sha256

3.1.1

backward changes

• Added the writeQueue* options, trying to resolve issue#108, see the API Documentation below.

3.0.0

Non-backward changes

• All the *Sync functions were removed, every operation is now asynchronous
• All the persist* functions were removed
• Nothing is held up in RAM use your own memory caching module, i.e. nano-cache
• Node 7.6+ is required now, we're using async/await
• continuous and interval options were removed, since we immediately persist to disk now, asynchronously
• forEach callback now accepts an object callback({key, value}) instead of 2 arguments callback(key, value)

2.0.0

Non-backward changes

• filenames on the file system are now md5 hashed now and the structure of the saved data has changed to include the ttl in them.
• no longer need/support a options.ttlDir, since the ttls are now stored in the same file as each value
• added expiredInterval option
• added forgiveParseErrors option

1.0.0

Mostly non-backward changes

• storage.getItem() now returns a promise
• storage.valuesWithKeyMatch() no longer accepts a callback
• storage.values() no longer accepts a callback
• storage.key() is gone
• The default dir is now process.cwd() + (dir || '.node-persist/storage'), unless you use an absolute path
• added storage.get(), alias to getItem()
• added storage.set(), alias to setItem()
• added storage.del(), storage.rm(), as aliases to removeItem()
• Keys, on the file system are base64 encoded with the replacement of the /

API Documentation

async init(options, [callback])

if the storage dir is new, it will create it

Options

You can pass init() an options object to customize the behavior of node-persist

These are the defaults

1await storage.init({
2	// ⚠️ Watch out: The folder should only be used by node-persist and only have valid storage files.
3	// Otherwise you might use 'forgiveParseErrors: true'.
4	dir: 'relative/path/to/persist',
5
6	stringify: JSON.stringify,
7
8	parse: JSON.parse,
9
10	encoding: 'utf8',
11
12	// can also be custom logging function
13	logging: false,  
14
15	// ttl* [NEW], can be true for 24h default or a number in MILLISECONDS or a valid Javascript Date object
16	ttl: false,
17
18	// every 2 minutes the process will clean-up the expired cache
19	expiredInterval: 2 * 60 * 1000, 
20
21    	// in some cases, you (or some other service) might add non-valid storage files to your
22    	// storage dir, i.e. Google Drive, make this true if you'd like to ignore these files and not throw an error
23	forgiveParseErrors: false,
24	
25	// instead of writing to file immediately, each "file" will have its own mini queue to avoid corrupted files, keep in mind that this would not properly work in multi-process setting.
26	writeQueue: true, 
27	
28	// how often to check for pending writes, don't worry if you feel like 1s is a lot, it actually tries to process every time you setItem as well
29	writeQueueIntervalMs: 1000, 
30	
31	// if you setItem() multiple times to the same key, only the last one would be set, BUT the others would still resolve with the results of the last one, if you turn this to false, each one will execute, but might slow down the writing process.
32	writeQueueWriteOnlyLast: true, 
33
34	// Limit the number of concurrently used file descriptors to avoid Error: EMFILE: too many open files
35	// Defaults to Infinity for maximum performance but YMMV depending on your OS and how you use the library
36	maxFileDescriptors: 512
37});
38

async getItem(key)

This function will get the value for that key stored on disk

1let value = await storage.getItem('obj');

async setItem(key, value, [options])

This function sets 'key' in your database to 'value'

1await storage.setItem('fibonacci',[0,1,1,2,3,5,8]);
2await storage.setItem(42,'the answer to life, the universe, and everything.');
3await storage.setItem(42,'the answer to life, the universe, and everything.', {ttl: 1000*60 /* 1 min */ });

* The only option available when calling setItem(key, value, option) is {ttl: Number|Date}

async updateItem(key, value, [options])

This function updates a 'key' in your database with a new 'value' without touching the ttl, however, if the key was not found or if it was expired a new item will get set

1await storage.updateItem(42,'the answer to life, the universe, and everything.', {ttl: 1000*60*10 /* 10 minutes */ });
2await storage.updateItem(42,'means nothing, do not trust wikipedia'); // ttl is still the same, will expired in 10 minutes since it was first set

* The only option available when calling updateItem(key, value, option) is {ttl: Number|Date}

async removeItem(key)

This function immediately deletes it from the file system asynchronously

1await storage.removeItem('me');

async clear()

This function immediately deletes all files from the file system asynchronously.

1await storage.clear();

async values()

This function returns all of the values

1await storage.setItem("batman", {name: "Bruce Wayne"});
2await storage.setItem("superman", {name: "Clark Kent"});
3console.log(await storage.values()); //output: [{name: "Bruce Wayne"},{name: "Clark Kent"}]

async valuesWithKeyMatch(match)

This function returns all of the values matching a string or RegExp

1await storage.setItem("batman", {name: "Bruce Wayne"});
2await storage.setItem("superman", {name: "Clark Kent"});
3await storage.setItem("hulk", {name: "Bruce Banner"});
4console.log(await storage.valuesWithKeyMatch('man')); //output: [{name: "Bruce Wayne"},{name: "Clark Kent"}]
5// also accepts a Regular Expression
6console.log(await storage.valuesWithKeyMatch(/man/)); //output: [{name: "Bruce Wayne"},{name: "Clark Kent"}]

async keys()

this function returns an array of all the keys in the database.

1console.log(await storage.keys()); // ['batman', 'superman']

async length()

This function returns the number of keys stored in the database.

1console.log(await storage.length()); // 2

async forEach(callback)

This function iterates over each key/value pair and executes an asynchronous callback as well

1storage.forEach(async function(datum) {
2	// use datum.key and datum.value
3});

Factory method

create(options) - synchronous, static method

If you choose to create multiple instances of storage, you can. Just avoid using the same dir for the storage location. You still have to call init after create - you can pass your configs to either create or init

1const storage = require('node-persist');
2const myStorage = storage.create({dir: 'myDir', ttl: 3000});
3await myStorage.init();

Tests

npm install
npm test

Simon Last