Bloom Filter in JavaScript based on https://www.badykov.com/ethereum/2017/10/29/ethereum-bloom-filter/

js

#!/usr/bin/env node

var bigInt = require("big-integer");

var Web3 = require('web3');
const web3 = new Web3(new Web3.providers.HttpProvider("https://mainnet.infura.io/zWDtcNMhNMHMyMYpiVs5"))

const createBloom = function (data) {
  return addBloom(0, data)
}

const bit_numbers = function(s) {
  s1 = s.substring(2,6) // byte pair 1
  b1 = parseInt(s1,16) & 2047
  s2 = s.substring(6,10) // byte pair 2
  b2 = parseInt(s2,16) & 2047
  s3 = s.substring(10,14) // byte pair 3
  b3 = parseInt(s3,16) & 2047
  return [b1,b2,b3]
}

const add_bits = function(binaryfilter, bits) {
  result = new bigInt(binaryfilter)
    .or(bigInt(2).pow(bits[0]))
    .or(bigInt(2).pow(bits[1]))
    .or(bigInt(2).pow(bits[2]))
  return result
}

const addBloom = function (binaryfilter, data) {
  return add_bits(binaryfilter, bit_numbers(web3.sha3(data)))
}

const contains = function (current_bloom, data) {
  return (current_bloom.or(createBloom(data)).equals(current_bloom))
}


bloomFilter = createBloom ("rock")
console.log("createBloom('rock')")
console.log(bloomFilter.toString())
bloomFilter = addBloom(bloomFilter, "blues")
console.log("addBloom('blues')")
console.log(bloomFilter.toString())
console.log("contains 'punk'")
console.log(contains(bloomFilter, "punk"))
console.log("contains 'rock'")
console.log(contains(bloomFilter, "rock"))
console.log("contains 'blues'")
console.log(contains(bloomFilter, "blues"))