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lodash/lodash.unzipwith/index.js
2018-02-03 19:13:33 -08:00

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2.4 KiB
JavaScript

/**
* lodash 3.8.0 (Custom Build) <https://lodash.com/>
* Build: `lodash modern modularize exports="npm" -o ./`
* Copyright 2012-2015 The Dojo Foundation <http://dojofoundation.org/>
* Based on Underscore.js 1.8.3 <http://underscorejs.org/LICENSE>
* Copyright 2009-2015 Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors
* Available under MIT license <https://lodash.com/license>
*/
var arrayMap = require('lodash._arraymap'),
bindCallback = require('lodash._bindcallback'),
unzip = require('lodash.unzip');
/**
* A specialized version of `_.reduce` for arrays without support for callback
* shorthands and `this` binding.
*
* @private
* @param {Array} array The array to iterate over.
* @param {Function} iteratee The function invoked per iteration.
* @param {*} [accumulator] The initial value.
* @param {boolean} [initFromArray] Specify using the first element of `array`
* as the initial value.
* @returns {*} Returns the accumulated value.
*/
function arrayReduce(array, iteratee, accumulator, initFromArray) {
var index = -1,
length = array.length;
if (initFromArray && length) {
accumulator = array[++index];
}
while (++index < length) {
accumulator = iteratee(accumulator, array[index], index, array);
}
return accumulator;
}
/**
* This method is like `_.unzip` except that it accepts an iteratee to specify
* how regrouped values should be combined. The `iteratee` is bound to `thisArg`
* and invoked with four arguments: (accumulator, value, index, group).
*
* @static
* @memberOf _
* @category Array
* @param {Array} array The array of grouped elements to process.
* @param {Function} [iteratee] The function to combine regrouped values.
* @param {*} [thisArg] The `this` binding of `iteratee`.
* @returns {Array} Returns the new array of regrouped elements.
* @example
*
* var zipped = _.zip([1, 2], [10, 20], [100, 200]);
* // => [[1, 10, 100], [2, 20, 200]]
*
* _.unzipWith(zipped, _.add);
* // => [3, 30, 300]
*/
function unzipWith(array, iteratee, thisArg) {
var length = array ? array.length : 0;
if (!length) {
return [];
}
var result = unzip(array);
if (iteratee == null) {
return result;
}
iteratee = bindCallback(iteratee, thisArg, 4);
return arrayMap(result, function(group) {
return arrayReduce(group, iteratee, undefined, true);
});
}
module.exports = unzipWith;