injective-map

injective-map implements a 1-to-1 map-like object with unique keys and values. This is useful if you need to ensure that each value only occurs exactly once. It is compatible with the standard Map type but also provides additional methods for finding the key for a particular value or deleting a value from the map.

Install

# If you use npm
npm install injective-map

# If you use yarn
yarn add injective-map

Usage

import { InjectiveMap, InjectiveMapLike } from "injective-map";

// injective-map provides a class `InjectiveMap<K, V>`
const injectiveMap = new InjectiveMap<string, number>();

// injective-map also provides an interface, `InjectiveMapLike<K, V>` that the class implements
const injectiveMapLike: InjectiveMapLike<string, number> = injectiveMap;

// You can also specify some configuration options when instantiating the `InjectiveMap`
const anotherInjectiveMap = new InjectiveMap<string, number>({
  // `entries` can be used to specify initial entries that the map is instantiated with
  // You can specify it as an array of key-value pairs, another Map object or as a plain object (provided your key type)
  entries: [["zero", 0], ["one", 1]],
  // `keyToValueMap` can be used to specify a custom Map-like object for storing the key to value map
  keyToValueMap: new Map<string, number>(),
  // `valueToKeyMap` can be used to specify a custom Map-like object for storing the value to key map
  valueToKeyMap: new Map<number, string>(),
});

// You can use `set` to set a key-value pair
injectiveMap.set("a", 0)
// injectiveMap = { "a": 0 }

// Like a normal map, if you `set` the same key, the value is overwritten
injectiveMap.set("a", 1)
// injectiveMap = { "a": 1 }

// Unlike a normal map, if you `set` the another key with a value that is already in use, the old key is removed
injectiveMap.set("b", 1)
// injectiveMap = { "b": 1 }

injectiveMap.set("c", 2)
// injectiveMap = { "b": 1, "c": 2 }

// You can check if the map has a certain key using `hasKey` or just `has` like in a normal map
injectiveMap.hasKey("b")
// true
injectiveMap.has("a")
// false

// You can check if the map has a certain value using `hasValue`
injectiveMap.hasValue(1)
// true
injectiveMap.hasValue(0)
// false

// You can get the value corresponding to a key with `getValue` or just `get` like in a normal map
injectiveMap.getValue("b")
// 1
injectiveMap.get("a")
// undefined

// You can get the key corresponding to a value with `getKey`
injectiveMap.getKey(1)
// "b"
injectiveMap.getKey(0)
// undefined

// You can delete a key using `deleteKey` or just `delete` like in a normal map
injectiveMap.deleteKey("b")
// true
// injectiveMap = { "c": 2 }
injectiveMap.delete("a")
// false
// injectiveMap = { "c": 2 }

// You can also delete by `value` using `deleteValue`
injectiveMap.deleteValue(2)
// true
// injectiveMap = {}

License

MIT