react-native/Libraries/Utilities/groupByEveryN.js
Sophie Alpert 1490ab12ef Update license headers for MIT license
Summary:
Includes React Native and its dependencies Fresco, Metro, and Yoga. Excludes samples/examples/docs.

find: ^(?:( *)|( *(?:[\*~#]|::))( )? *)?Copyright (?:\(c\) )?(\d{4})\b.+Facebook[\s\S]+?BSD[\s\S]+?(?:this source tree|the same directory)\.$
replace: $1$2$3Copyright (c) $4-present, Facebook, Inc.\n$2\n$1$2$3This source code is licensed under the MIT license found in the\n$1$2$3LICENSE file in the root directory of this source tree.

Reviewed By: TheSavior, yungsters

Differential Revision: D7007050

fbshipit-source-id: 37dd6bf0ffec0923bfc99c260bb330683f35553e
2018-02-16 18:31:53 -08:00

51 lines
1.1 KiB
JavaScript

/**
* Copyright (c) 2015-present, Facebook, Inc.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*
* @providesModule groupByEveryN
* @flow
*/
/**
* Useful method to split an array into groups of the same number of elements.
* You can use it to generate grids, rows, pages...
*
* If the input length is not a multiple of the count, it'll fill the last
* array with null so you can display a placeholder.
*
* Example:
* groupByEveryN([1, 2, 3, 4, 5], 3)
* => [[1, 2, 3], [4, 5, null]]
*
* groupByEveryN([1, 2, 3], 2).map(elems => {
* return <Row>{elems.map(elem => <Elem>{elem}</Elem>)}</Row>;
* })
*/
'use strict';
function groupByEveryN<T>(array: Array<T>, n: number): Array<Array<?T>> {
var result = [];
var temp = [];
for (var i = 0; i < array.length; ++i) {
if (i > 0 && i % n === 0) {
result.push(temp);
temp = [];
}
temp.push(array[i]);
}
if (temp.length > 0) {
while (temp.length !== n) {
temp.push(null);
}
result.push(temp);
}
return result;
}
module.exports = groupByEveryN;