题解 | #数组扁平化#

const _flatten = arr => {
	// 补全代码
	let newArr = [];
	function dealArr(_arr, _index) {
		for (let i = 0; i < _arr.length; i++) {
			if (!Array.isArray(_arr[i])) {
				newArr[_index] = _arr[i]
				_index++
			} else {
				dealArr(_arr[i], _index)
			}
		}

	}
	for (let i = 0; i < arr.length; i++) {
		if (!Array.isArray(arr[i])) {
			newArr[i] = arr[i]
		} else {
			dealArr(arr[i], i)
		}
	}
	return newArr
}