The multimap data structure is a map in which more than one value may be stored under each key.

$ npm install @github/multimap

import MultiMap from '@github/multimap'

const map = new MultiMap<string, number>()
map.set('a', 1)
map.set('a', 2)
map.get('a') // => Set([1, 2])
map.has('a') // => true
map.size // => 1

• MultiMap() - Create an empty map.
• MultiMap(iterable) - Create a map with values from an iterable yielding key value pairs: new MultiMap([['k', 1], ['k', 2]])

• get(key) - Retrieve the Set of values stored under a key or the empty Set if the key does not exist.
• set(key, value) - Add a value to the key's set without removing previous values. Returns the map so set can be chained.
• has(key) - Returns true if a value is stored under the key.
• delete(key) - Remove key and all of key's values. Returns true if the key existed.
• delete(key, value) - Remove a value from the key's set. Returns true if the key and value existed.
• drain(value) - Remove a value from all keys that reference it. Returns an array of keys removed.
• clear() - Remove all keys and values to empty the map.
• keys() - An iterator of map keys.
• values() - An iterator of Sets of values for all keys.
• entries() - An iterator of [key, Set] pairs.

• size - The number of keys in the map.

npm install
npm test

Distributed under the MIT license. See LICENSE for details.