Javascript实现嵌套数组扁平化

 1  function flat(arr, result) {
 2       arr.forEach((item, index) => {
 3         if (!Array.isArray(item)) {
 4           result.push(item)
 5         } else {
 6           flat(item, result)
 7         }
 8       })
 9       return result
10     }
11     var testArr = [10, 2, [3, 4, [5, [55]]]]
12     var result = []
13     console.log(flat(testArr, result))

1     var testArr = [10, 2, [3, 4, [5, [55]]]]
2     console.log(testArr.toString())

var testArr = [10, 2, [3, 4, [5, [55]]]]
    console.log(testArr.flat(Infinity))