'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)
}