@duckduckgo/jsbloom

1.0.2 • Public • Published

#jsbloom

Build Status

A fast bloom filter implementation in JavaScript using the djb2 and sdbm algorithms.

From Less Hashing, Same Performance: Building a Better Bloom Filter by Adam Kirsch et al, it is possible to build k hash values from only 2 unique values. Hence, it is sufficient to have two unique hashes generated.

Usage

var filter = new JSBloom(items, false_probability_chance);

filter.addEntry("xyz");

filter.checkEntry("xyz"); // returns true

filter.checkEntry("yz"); // returns false

Testing

Testing is done with mocha and chai

npm install mocha chai
mocha

Parameters

items: ceiling of entries to add
false_probability_chance: chance of false positives to occur

JSBloom will automatically generate the needed bit array and amount of hashes needed to meet your requirements.

API reference

addEntry(str): adds str to bloom filter
addEntries(arr): iterates over arr and adds every entry within
checkEntry(str): checks if str in filter, returns false if definitely not, true if maybe
importData(base64, [number_of_hashes]): loads a base 64 LZW compressed Uint8Array
exportData(): returns base 64 encoded Uint8Array LZW as string
exportData(callback): returns the base 64 encoded Uint8Array LZW compressed to provided callback

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Install

npm i @duckduckgo/jsbloom

Weekly Downloads

229

Version

1.0.2

License

MIT

Unpacked Size

18.4 kB

Total Files

6

Last publish

Collaborators

  • jakeddg
  • adewes
  • mariag
  • altenone
  • charlie-b
  • muodov
  • jdorw
  • moollaza
  • dharb
  • kdzwinel
  • sammacbeth