A bi-directional map, with unique keys to unique values. Internally, its a map and its inverse map which allows value to be looked up through key, and key through value. Eg. email id <-> person name.

const BiMap = require('extra-bimap');
// : all Map() functions available

var m = new BiMap();
// BiMap [Map] {}

m.set(1, 'a');
// BiMap [Map] { 1 => 'a' }

m.set(2, 'b');
// BiMap [Map] { 1 => 'a', 2 => 'b' }

m.set(2, 'a');
// Error: BiMap pair is not unique

m.inverse;
// BiMap [Map] { 'a' => 1, 'b' => 2 }

m.inverse.set('a', 2);
// Error: BiMap pair is not unique

m.inverse.set('b', 3);
// BiMap [Map] { 'a' => 1, 'b' => 3 }

m.inverse.inverse
// BiMap [Map] { 1 => 'a', 3 => 'b' }

m.delete(1);
// BiMap [Map] { 3 => 'b' }

m.inverse.has('a')
// false

reference

| Name | Action |---------------------|------- | BiMap | Creates a bi-directional map, with unique keys to unique values. | inverse | Gives reversed bi-directional map. | clear | Removes all elements from map. | delete | Removes the specified element from map. | set | Adds or updates an element with a specified key and a value to map. | size | Same as Map. | entries | Same as Map. | forEach | Same as Map. | get | Same as Map. | has | Same as Map. | keys | Same as Map. | values | Same as Map. | @@iterator | Same as Map.