Features

• Familiar: SameValueMap and SameValueSet extend JavaScript's built-in Map and Set
• Compliant: maintains all the invariants of Map and Set including method return values and even iteration order!
• Tiny: less than 350 bytes minzipped!

Install

$ npm i svkc

Huh?

A key in a Map or a value in a Set can only occur once. But how is the key or value's uniqueness determined? JavaScript's Map and Set use the sameValueZero algorithm when checking if two keys or values are equal. The algorithm considers +0 and -0 to be equal, but they are actually two different values due to how IEEE floating point numbers work. This means that both new Map([[0, 'zero'], [-0, 'negative zero']]).size and new Set([0, -0]).size return 1 rather than 2.

This package provides SameValueMap and SameValueSet that behave identically to Map and Set except they consider +0 and -0 to be different values.

Usage

Just use like a normal Map or Set!

import { SameValueMap, SameValueSet } from 'svkc'

const sameValueMap = new SameValueMap()
sameValueMap.set(1, `one`)
sameValueMap.set(0, `zero`)
sameValueMap.set(-0, `negative zero`)
sameValueMap.set(-1, `negative one`)

console.log(sameValueMap.get(0))
//=> zero

console.log(sameValueMap.get(-0))
//=> negative zero

console.log([...sameValueMap])
//=> [ [ 1, 'one' ], [ 0, 'zero' ], [ -0, 'negative zero' ], [ -1, 'negative one' ] ]

sameValueMap.delete(0)

console.log(sameValueMap.has(0))
//=> false

console.log(sameValueMap.has(-0))
//=> true

const sameValueSet = new SameValueSet()
sameValueSet.add(1)
sameValueSet.add(0)
sameValueSet.add(-0)
sameValueSet.add(-1)

console.log(sameValueSet.has(0))
//=> true

console.log(sameValueSet.has(-0))
//=> true

console.log([...sameValueSet])
//=> [ 1, 0, -0, -1 ]

sameValueSet.delete(0)

console.log(sameValueSet.has(0))
//=> false

console.log(sameValueSet.has(-0))
//=> true

Contributing

Stars are always welcome!

For bugs and feature requests, please create an issue.

For pull requests, please read the contributing guidelines.

License

Apache License 2.0

This is not an official Google product.