sortBy.js
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var baseCallback = require('../internal/baseCallback'),
baseMap = require('../internal/baseMap'),
baseSortBy = require('../internal/baseSortBy'),
compareAscending = require('../internal/compareAscending'),
isIterateeCall = require('../internal/isIterateeCall');
/**
* Creates an array of elements, sorted in ascending order by the results of
* running each element in a collection through `iteratee`. This method performs
* a stable sort, that is, it preserves the original sort order of equal elements.
* The `iteratee` is bound to `thisArg` and invoked with three arguments:
* (value, index|key, collection).
*
* 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`.
*
* @static
* @memberOf _
* @category Collection
* @param {Array|Object|string} collection The collection to iterate over.
* @param {Function|Object|string} [iteratee=_.identity] The function invoked
* per iteration.
* @param {*} [thisArg] The `this` binding of `iteratee`.
* @returns {Array} Returns the new sorted array.
* @example
*
* _.sortBy([1, 2, 3], function(n) {
* return Math.sin(n);
* });
* // => [3, 1, 2]
*
* _.sortBy([1, 2, 3], function(n) {
* return this.sin(n);
* }, Math);
* // => [3, 1, 2]
*
* var users = [
* { 'user': 'fred' },
* { 'user': 'pebbles' },
* { 'user': 'barney' }
* ];
*
* // using the `_.property` callback shorthand
* _.pluck(_.sortBy(users, 'user'), 'user');
* // => ['barney', 'fred', 'pebbles']
*/
function sortBy(collection, iteratee, thisArg) {
if (collection == null) {
return [];
}
if (thisArg && isIterateeCall(collection, iteratee, thisArg)) {
iteratee = undefined;
}
var index = -1;
iteratee = baseCallback(iteratee, thisArg, 3);
var result = baseMap(collection, function(value, key, collection) {
return { 'criteria': iteratee(value, key, collection), 'index': ++index, 'value': value };
});
return baseSortBy(result, compareAscending);
}
module.exports = sortBy;