--- /dev/null
+'use strict'
+
+/**
+ * Expose `arrayFlatten`.
+ */
+module.exports = arrayFlatten
+
+/**
+ * Recursive flatten function with depth.
+ *
+ * @param {Array} array
+ * @param {Array} result
+ * @param {Number} depth
+ * @return {Array}
+ */
+function flattenWithDepth (array, result, depth) {
+ for (var i = 0; i < array.length; i++) {
+ var value = array[i]
+
+ if (depth > 0 && Array.isArray(value)) {
+ flattenWithDepth(value, result, depth - 1)
+ } else {
+ result.push(value)
+ }
+ }
+
+ return result
+}
+
+/**
+ * Recursive flatten function. Omitting depth is slightly faster.
+ *
+ * @param {Array} array
+ * @param {Array} result
+ * @return {Array}
+ */
+function flattenForever (array, result) {
+ for (var i = 0; i < array.length; i++) {
+ var value = array[i]
+
+ if (Array.isArray(value)) {
+ flattenForever(value, result)
+ } else {
+ result.push(value)
+ }
+ }
+
+ return result
+}
+
+/**
+ * Flatten an array, with the ability to define a depth.
+ *
+ * @param {Array} array
+ * @param {Number} depth
+ * @return {Array}
+ */
+function arrayFlatten (array, depth) {
+ if (depth == null) {
+ return flattenForever(array, [])
+ }
+
+ return flattenWithDepth(array, [], depth)
+}