相反，您可以使用.reduce()和内部.map()和.filter()方法。内部的.map()方法会将给定答案数组中的所有对象转换为ids数组。.filter()方法将确保我们只抓取具有content或"comment"的对象的id。外部reduce方法用于将内部.map()方法产生的所有数组整理成一个更大的数组。这是使用扩展语法将旧的累积数组与新Map的值合并来完成的。
参见以下示例：

const obj = { "comments": [ { "id": 1, "content": "comment", "answers": [] }, { "id": 2, "content": "comment", "answers": [ { "id": 25, "content": "comment" } ] }, { "id": 3, "content": "comment", "answers": [ { "id": 72, "content": "comment" }, { "id": 105, "content": "comment" } ] }, { "id": 4, "content": "comment", "answers": [] } ] }

const res = obj.comments.reduce(
  (acc, {id, answers, content}) => [...acc, ...answers.filter(({content}) => content === "comment").map(({id}) => id)],
[]);

console.log(res);

话虽如此，我更喜欢使用.flatMap()而不是.reduce()：

const obj = { "comments": [ { "id": 1, "content": "comment", "answers": [] }, { "id": 2, "content": "comment", "answers": [ { "id": 25, "content": "comment" } ] }, { "id": 3, "content": "comment", "answers": [ { "id": 72, "content": "comment" }, { "id": 105, "content": "comment" } ] }, { "id": 4, "content": "comment", "answers": [] } ] }

const res = obj.comments.flatMap(({id, answers}) => answers.filter(({content}) => content === "comment").map(({id}) => id));

console.log(res);

请试试这个例子

const data = {
  comments: [
    {
      id: 1,
      content: "comment",
      answers: [],
    },
    {
      id: 2,
      content: "comment",
      answers: [
        {
          id: 25,
          content: "comment",
        },
      ],
    },
    {
      id: 3,
      content: "comment",
      answers: [
        {
          id: 72,
          content: "comment",
        },
        {
          id: 105,
          content: "comment",
        },
      ],
    },
    {
      id: 4,
      content: "comment",
      answers: [],
    },
  ],
};

const output = data.comments
  .map((entry) => entry.answers.map((item) => item.id))
  .flat();

const anotherOutput = data.comments.map(({ id }) => id);

console.log(output, anotherOutput);

看

• Array.prototype.map()
• Array.prototype.flat()