如何根据每个对象中的字段值过滤数组并将剩余字段分组到该对象下答案

【问题标题】：How to filter an array based on a field value in each object and group the remaining fields under that object如何根据每个对象中的字段值过滤数组并将剩余字段分组到该对象下
【发布时间】：2021-12-02 14:09:30
【问题描述】：

我正在尝试修改数组。我有以下 json。

    [
        { state: "NY", key: "A", value: "Alarm" },
        { state: "CT", key: "A", value: "Alarm" },
        { state: "NH", key: "A", value: "Alarm" },
        { state: "CT", key: "B", value: "Audible and Etched" },
        { state: "NH", key: "B", value: "Audible and Etched" },
        { state: "NY", key: "AA", value: "Active Disabling and Anti-Theft" },
        { state: "FL", key: "B", value: "Audible and Etched" },
        { state: "FL", key: "A", value: "Alarm" },
        { state: "FL", key: "AA", value: "Active Disabling and Anti-Theft" }
    ]

根据每个唯一状态，我需要将键、值分组到下拉数组中，如下所示

    [{
        state: "NY",
        dropdown: [
            { key: "A", value: "Alarm" },
            { key: "AA", value: "Active Disabling and Anti-Theft" }
        ]
    },
    {
        state: "CT",
        dropdown: [
            { key: "A", value: "Alarm" },
            { key: "B", value: "Audible and Etched" }
        ]
    },
    {
        state: "NH",
        dropdown: [
            { key: "A", value: "Alarm" },
            { key: "B", value: "Audible and Etched" }
        ]
    },
    {
        state: "FL",
        dropdown: [
            { key: "A", value: "Alarm" },
            { key: "B", value: "Audible and Etched" },
            { key: "AA", value: "Active Disabling and Anti-Theft" }
        ]
    }]

任何帮助将不胜感激。谢谢。

【问题讨论】：

到目前为止你尝试过什么？需要明确的是，StackOverflow 不是一个有人为你做作业的地方，你需要付出一些努力。

标签： javascript node.js angular typescript

【解决方案1】：

您可以使用Array.reduce获取修改后的数组。

const inputArray = [
        { state: "NY", key: "A", value: "Alarm" },
        { state: "CT", key: "A", value: "Alarm" },
        { state: "NH", key: "A", value: "Alarm" },
        { state: "CT", key: "B", value: "Audible and Etched" },
        { state: "NH", key: "B", value: "Audible and Etched" },
        { state: "NY", key: "AA", value: "Active Disabling and Anti-Theft" },
        { state: "FL", key: "B", value: "Audible and Etched" },
        { state: "FL", key: "A", value: "Alarm" },
        { state: "FL", key: "AA", value: "Active Disabling and Anti-Theft" }
];

const result = inputArray.reduce((acc, item) => {
   const exist = acc.find(e => e.state == item.state);
   if (exist) {
      exist.dropdown.push({
          key: item.key,
          value: item.value
      })
   } else {
      acc.push({
         state: item.state,
         dropdown: [{
           key: item.key,
           value: item.value
         }]
      });
   }
   return acc;
}, []);

console.log(result);

【讨论】：