unique-map

Returns a copy of a Map or Object with duplicate values removed.

This module only tests values, because it’s impossible for a Map or Object to have a duplicate key. (If you want to use Map/Object keys as a basis for testing uniqueness, use the unique-map-by module instead.)

Optionally lets you set a numeric limit on total entries in the returned Map/Object.

Installation

npm install unique-map --save

The module exports a single function.

Usage Example

const uniqueMap = require('unique-map')

const map = new Map([
  [1, 'A'],
  [2, 'A'],
  [3, 'B'],
])

const u = uniqueMap(map)
u.size // 2
u.get(1) // 'A'
u.get(2) // undefined
u.get(3) // 'B'

You can also use the limit argument to cap the number of total entries returned:

const u = uniqueMap(map, {limit: 1})
u.size // 1
u.get(1) // 'A'
u.get(2) // undefined
u.get(3) // undefined

The module also works just as well with Objects:

const uniqueMap = require('unique-map')

const obj = {
  1: 'A',
  2: 'A',
  3: 'B',
}

const u = uniqueMap(obj)
u[1] // 'A'
u[2] // undefined
u[3] // 'B'

Related Projects

• deduplicate
• unique-array-by
• unique-iterable
• unique-iterable-by
• unique-map-by