[ReactNative] OSS CameraRoll

Libraries/Utilities/groupByEveryN.js

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+/**
+ * Copyright 2004-present Facebook. All Rights Reserved.
+ *
+ * @providesModule groupByEveryN
+ */
+
+/**
+ * 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(array, n) {
+  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;