javascript，nodejs中的迭代[关闭]答案

【问题标题】：iteration in javascript, nodejs [closed]javascript，nodejs中的迭代[关闭]
【发布时间】：2019-12-06 10:54:24
【问题描述】：

我有这样的数据： -

[
{"title": "A Hug Is Warm","id": "69","level": "4","act_title": "Alphabet","act_id": "69_1d"},
{"title": "A Hug Is Warm","id": "69","level": "4","act_title": "Recording","act_id": "69_rec"},
{"title": "A Hug Is Warm","level": "4","id": "69","act_title": "Print","act_id": "69_pr_1"},
.........
];

又想回来：......

[{
        "title": "A Hug Is Warm",
        "id": "69",
        "level": "4",
        "activities": [{"act_title": "Alphabet",act_id": "69_1d"},
            {"act_title": "Recording","act_id": "69_rec"},
            {"act_title": "Print","act_id": "69_pr_1"}
        ]
    },
    ..........
]

在php中使用多维数组很容易实现。

【问题讨论】：

标签： javascript node.js multidimensional-array

【解决方案1】：

你可以使用Array.reduce():

var arr = [{
    "title": "A Hug Is Warm",
    "id": "69",
    "level": "4",
    "act_title": "Alphabet",
    "act_id": "69_1d"
  },
  {
    "title": "A Hug Is Warm",
    "id": "69",
    "level": "4",
    "act_title": "Recording",
    "act_id": "69_rec"
  },
  {
    "title": "A Hug Is Warm",
    "level": "4",
    "id": "69",
    "act_title": "Print",
    "act_id": "69_pr_1"
  },
  {
    "title": "A Hug Is Warm",
    "id": "70",
    "level": "4",
    "act_title": "Alphabet",
    "act_id": "69_1d"
  },
  {
    "title": "A Hug Is Warm",
    "id": "70",
    "level": "4",
    "act_title": "Recording",
    "act_id": "69_rec"
  },
  {
    "title": "A Hug Is Warm",
    "level": "4",
    "id": "70",
    "act_title": "Print",
    "act_id": "69_pr_1"
  }
];

var res = arr.reduce((acc, item) => {
  let existItem = acc.find(({id}) => id === item.id);
  if (existItem) {
    existItem.activities.push({
      act_title: item.act_title,
      act_id: item.act_id
    });
  } else {
    acc.push({
      title: item.title,
      level: item.level,
      id: item.id,
      activities: [{
        act_title: item.act_title,
        act_id: item.act_id
      }]
    });
  }
  return acc;
}, []);

console.log(res);

【讨论】：