JavaScript's keyed collections (Map & Set) with SameValue semantics!
- Familiar:
SameValueMapandSameValueSetextend JavaScript's built-inMapandSet - Compliant: maintains all the invariants of
MapandSetincluding method return values and even iteration order! - Tiny: less than 350 bytes minzipped!
$ npm i svkcA 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.
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))
//=> trueStars are always welcome!
For bugs and feature requests, please create an issue.