zipWith.js
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define(['../function/restParam', './unzipWith'], function(restParam, unzipWith) {
/** Used as a safe reference for `undefined` in pre-ES5 environments. */
var undefined;
/**
* This method is like `_.zip` except that it accepts an iteratee to specify
* how grouped 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} [arrays] The arrays to process.
* @param {Function} [iteratee] The function to combine grouped values.
* @param {*} [thisArg] The `this` binding of `iteratee`.
* @returns {Array} Returns the new array of grouped elements.
* @example
*
* _.zipWith([1, 2], [10, 20], [100, 200], _.add);
* // => [111, 222]
*/
var zipWith = restParam(function(arrays) {
var length = arrays.length,
iteratee = length > 2 ? arrays[length - 2] : undefined,
thisArg = length > 1 ? arrays[length - 1] : undefined;
if (length > 2 && typeof iteratee == 'function') {
length -= 2;
} else {
iteratee = (length > 1 && typeof thisArg == 'function') ? (--length, thisArg) : undefined;
thisArg = undefined;
}
arrays.length = length;
return unzipWith(arrays, iteratee, thisArg);
});
return zipWith;
});