@bitarray/es6

A BitArray class for easy and native-like operations on sequences of bits.

Rationale

The library implements ArrayBuffers behind the hood. This allows for:

• optimal memory usage: each bit is effectively coded in just one bit in memory, as opposed to being coded as, e.g. booleans or integers in regular arrays.

• efficient bitwise operations: operations treat 32 bits at once, as opposed to dealing with entries one by one in regular arrays.

:bulb: It comes at the cost that accessing a single bit at a given index will be slightly more expensive than accessing the value stored in a regular array: indeed, the interesting bit needs to be extracted once a Uint32 value has been found first.

Having said that, in the very vast majority of cases, any difference either way should be unnoticeable; and you may very well opt to use this library for the sole reason that it provides a convenient native-like interface for your needs.

Compatibility

The library relies on the Proxy object, which is an ES6 (aka ES2015) feature. It can NOT be polyfilled (to the extent it is used by the library).

Note: standard TypedArray is also a feature of ecmascript ES6.

Installation

npm install @bitarray/es6

or

yarn add @bitarray/es6

Usage

Usage is same as for any standard typed array. You may check the MDN documentation for details. This is because the BitArray object extends @bitarray/typedarray. Check it for details.

It adds bitwise operations on top.

Instantiating

import BitArray from "@bitarray/es6"

const bits = BitArray.from("11001010");

const otherbits = new BitArray(12); // 12 bits, the values of which default to zero.

Bitwise operations

bits.count; // === 4; number of bits set to 1.

// same as bits.and(otherbits)
(bits)['&'](otherbits); // an instance holding a sequence of eight zeros

// same as bits.or(otherbits)
(bits)['|'](otherbits); // 11001010

// same as bits.xor(otherbits)
(bits)['^'](otherbits); // 11001010

Iterating

for (let i=0; i<bits.length; i++)
  // do something with bits[i]

bits.forEach((val, i, arr) => { /* do something */ });

for (let i in bits)
  // do something with bits[i]

for (let bit of bits)
  // do something with bit

Indexes & values

Object.keys(bits);    // [0, 1, 2, 3, 4, 5, 6, 7]
Object.values(bits);  // [1, 1, 0, 0, 1, 0, 1, 0]
Object.entries(bits); // [["0", 1], ["1", 1], ["2", 0], ["3", 0], ...]

License