数组偏平化

数组扁平化

数组扁平化就是将多维数组转化为一维数组

function flattenArray(arr) {
  const flattened = [].concat(...arr);
  return flattened.some(item => Array.isArray(item)) ? 
    flattenArray(flattened) : flattened;
}
 
const arr = [11, [22, 33], [44, [55, 66, [77, [88]], 99]]];
const flatArr = flattenArray(arr); 
console.log(flatArr) //[11,22,33,44,55,66,77,88,99]