在 JavaScript 中使用递归展平嵌套数组 [英] Flatten nested arrays using recursion in JavaScript

问题描述

我试图在保留顺序的同时展平嵌套数组，例如[[1, 2], 3, [4, [[5]]]] 应转换为[1, 2, 3, 4, 5].

I'm trying to flatten nested arrays while preserving the order, e.g. [[1, 2], 3, [4, [[5]]]] should be converted to [1, 2, 3, 4, 5].

我正在尝试使用递归来这样做，但下面的代码不起作用，我不明白为什么.我知道还有其他方法可以做到这一点，但我想知道这有什么问题.

I'm trying to use recursion in order to do so, but the code below does not work and I don't understand why. I know there are other methods to do it, but I'd like to know what's wrong with this.

function flatten (arr) {
  var newArr = [];
  for (var i = 0; i < arr.length; i++) {
    if (Array.isArray(arr[i])) {
      flatten(arr);
    } else {
      newArr.push(arr[i]);
    }
  }
  return newArr;
}

flatten([[1, 2], 3, [4, [[5]]]]);

谢谢

推荐答案

递归调用flatten时，需要将arr[i]传递给它，然后concat结果与 newArr.所以替换这一行:

When calling flatten recursively, you need to pass arr[i] to it and then concat the result with newArr. So replace this line:

flatten(arr);

与:

newArr = newArr.concat(flatten(arr[i]));

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