Lodash Uniq

var uniq = require('lodash.uniq');

import uniq from 'lodash.uniq';

var uniq = require('lodash.uniq');

// Basic deduplication
uniq([2, 1, 2]);
// => [2, 1]

// Sorted array optimization
uniq([1, 1, 2], true);
// => [1, 2]

// Custom comparison with iteratee
uniq([1, 2.5, 1.5, 2], function(n) {
  return Math.floor(n);
});
// => [1, 2.5]

// Property-based deduplication
uniq([{ 'x': 1 }, { 'x': 2 }, { 'x': 1 }], 'x');
// => [{ 'x': 1 }, { 'x': 2 }]

/**
 * Creates a duplicate-free version of an array, using SameValueZero
 * for equality comparisons, in which only the first occurence of each element
 * is kept. Providing `true` for `isSorted` performs a faster search algorithm
 * for sorted arrays. If an iteratee function is provided it's invoked for
 * each element in the array to generate the criterion by which uniqueness
 * is computed. The `iteratee` is bound to `thisArg` and invoked with three
 * arguments: (value, index, array).
 *
 * If a property name is provided for `iteratee` the created `_.property`
 * style callback returns the property value of the given element.
 *
 * If a value is also provided for `thisArg` the created `_.matchesProperty`
 * style callback returns `true` for elements that have a matching property
 * value, else `false`.
 *
 * If an object is provided for `iteratee` the created `_.matches` style
 * callback returns `true` for elements that have the properties of the given
 * object, else `false`.
 *
 * @alias unique
 * @param {Array} array The array to inspect.
 * @param {boolean} [isSorted] Specify the array is sorted.
 * @param {Function|Object|string} [iteratee] The function invoked per iteration.
 * @param {*} [thisArg] The `this` binding of `iteratee`.
 * @returns {Array} Returns the new duplicate-value-free array.
 */
function uniq(array, isSorted, iteratee, thisArg);

// Available as alias
var unique = uniq;

// Remove duplicates from unsorted array
uniq([2, 1, 2]);
// => [2, 1]

uniq([1, 3, 2, 1, 3]);
// => [1, 3, 2]

// Use isSorted flag for performance optimization
uniq([1, 1, 2], true);
// => [1, 2]

uniq([1, 2, 2, 3, 3, 3], true);
// => [1, 2, 3]

// Custom comparison logic
uniq([1, 2.5, 1.5, 2], function(n) {
  return Math.floor(n);
});
// => [1, 2.5]

// With thisArg binding
uniq([1, 2.5, 1.5, 2], function(n) {
  return this.floor(n);
}, Math);
// => [1, 2.5]

// Deduplicate by object property
uniq([{ 'x': 1 }, { 'x': 2 }, { 'x': 1 }], 'x');
// => [{ 'x': 1 }, { 'x': 2 }]

uniq([{ name: 'Alice' }, { name: 'Bob' }, { name: 'Alice' }], 'name');
// => [{ name: 'Alice' }, { name: 'Bob' }]

// Deduplicate by object pattern match
uniq([
  { 'user': 'barney', 'active': false },
  { 'user': 'fred', 'active': true },
  { 'user': 'pebbles', 'active': false }
], { 'active': false });
// => [{ 'user': 'barney', 'active': false }, { 'user': 'fred', 'active': true }]

// Deduplicate using property-value pair matching
var users = [
  { 'user': 'barney', 'active': false },
  { 'user': 'fred', 'active': true },
  { 'user': 'pebbles', 'active': false }
];

// Uses _.matchesProperty style callback
uniq(users, 'active', false);
// => [{ 'user': 'barney', 'active': false }, { 'user': 'fred', 'active': true }]