Arraysetjs NPM

arrayset

A dependency-free library for treating arrays like sets and performing set operations with an intuitive interface.

This library also includes a mutable version (ideal for use with Automerge or Immer).

Notes

arrayset will not itself introduce duplicates with any of its operations; however, it will not police the arrays you provide to remove duplicates.
arrayset does not guarantee the order of elements after set operations.
arrayset does not check arguments; make sure you're using it correctly!
arrayset supports providing comparison functions for use with objects, but this has not been tested or documented.

Normal (immutable) usage

import set from 'arraysetjs'

// existence:

set([1, 2, 3]).contains(2) // true
set([1, 2, 3]).contains(4) // false

// add/remove elements:

set([1, 2, 3]).add(4) // [1, 2, 3, 4]
set([1, 2, 3]).remove(2) // [1, 3]

// union:

set([1, 2, 3]).union([4, 5, 6]) // [1, 2, 3, 4, 5, 6]
set([1, 2, 3]).union([3, 4, 5]) // [1, 2, 3, 4, 5]

// intersection:

set([1, 2, 3]).intersection([4, 5, 6]) // []
set([1, 2, 3]).intersection([3, 4, 5]) // [3]

// difference:

set([1, 2, 3]).minus([1, 3]) // [2]

// create an arrayset instance:

set.fromArray([1, 2, 3, 2, 3]) // [1, 2, 3]

Mutable usage

The interface for mutable usage is exactly the same except the source array is modified. For example:

import set from 'arraysetjs'

const a = [1, 2, 3]
set.mutable(a).union([3, 4]) // a is now [1, 2, 3, 4]
// (which is also returned)

Contributing

This is a small library without a lot of activity, so generally I'll accept any reasonable enhancements. If there are big changes you would like to see, please raise an issue first to discuss.