'use strict';
|
var aCallable = require('../internals/a-callable');
|
var lengthOfArrayLike = require('../internals/length-of-array-like');
|
var toObject = require('../internals/to-object');
|
var getBuiltIn = require('../internals/get-built-in');
|
var arraySpeciesCreate = require('../internals/array-species-create');
|
|
var push = [].push;
|
|
// `Array.prototype.uniqueBy` method
|
// https://github.com/tc39/proposal-array-unique
|
module.exports = function uniqueBy(resolver) {
|
var that = toObject(this);
|
var length = lengthOfArrayLike(that);
|
var result = arraySpeciesCreate(that, 0);
|
var Map = getBuiltIn('Map');
|
var map = new Map();
|
var resolverFunction, index, item, key;
|
if (resolver != null) resolverFunction = aCallable(resolver);
|
else resolverFunction = function (value) {
|
return value;
|
};
|
for (index = 0; index < length; index++) {
|
item = that[index];
|
key = resolverFunction(item);
|
if (!map.has(key)) map.set(key, item);
|
}
|
map.forEach(function (value) {
|
push.call(result, value);
|
});
|
return result;
|
};
|
