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DᴀʀᴛʜVᴀᴅᴇʀ
Asked: 2023-11-08 01:48:22 +0800 CST

在 Node 中，如何将对象数组合并到新数组中，其中每个对象名称在字符串数组中都有其值？

  • 772

我有一个对象数组，如下所示：

const arr = [
    {
        "name": "Day",
        "value": "Monday"
    },
    {
        "name": "Month",
        "value": "November"
    },
    {
        "name": "Day",
        "value": "Monday"
    },
    {
        "name": "Month",
        "value": "December"
    },
    {
        "name": "Day",
        "value": "Friday"
    },
    {
        "name": "Month",
        "value": "November"
    },
    {
        "name": "Day",
        "value": "Friday"
    },
    {
        "name": "Month",
        "value": "December"
    }
]

但我需要将对象数组修改为：

const final = [
    {
        "name": "Day",
        "values": [
            "Monday",
            "Friday"
        ]
    },
    {
        "name": "Month",
        "values": [
            "November",
            "December"
        ]
    }
]

我可以用以下方法过滤掉重复项：

const filtered = arr.filter(
    (v, i, a) =>
      a.findIndex(v2 => v?.name === v2?.name && v?.value === v2?.value) === i
  );

但我坚持在没有Lodash或下划线的情况下以有效的方式执行此操作的方法，并且我尝试使用Object.assign()但我的实现不起作用：

const test = filtered.map(({ name, value }) =>
    Object.assign({ name, value: [] }, (name, value))
  );
console.log(test)

我想我以前见过这个问题并测试过以下答案：

在对象数组中，我可以组合具有相同名称但在字符串数组中具有值的对象吗？

node.js

1 个回答

  1. Best Answer

    使用带有预先分配的天和蛾元素的起始值的reduce ，使用Set自动忽略重复项，然后在减少所有内容后，将该集合转换为数组：

    const arr = [{
    name: "Day",
    value: "Monday",
  },{
    name: "Month",
    value: "November",
  },{
    name: "Day",
    value: "Monday",
  },{
    name: "Month",
    value: "December",
  },{
    name: "Day",
    value: "Friday",
  },{
    name: "Month",
    value: "November",
  },{
    name: "Day",
    value: "Friday",
  },{
    name: "Month",
    value: "December",
}];

// reduce the data to the form you need:
const final = arr.reduce(
  (resultSoFar, {name, value}) => {
    // find the "bin" to add this value to:
    let bin = resultSoFar.find((e) => e.name === name);
    // or make a new bin if there isn't one:
    if (!bin) resultSoFar.push(bin = { name, values: new Set() });
    // then add our value, and return the new result so far.
    bin.values.add(value);
    return resultSoFar;
  },
  // and start with `resultSoFar` being an empty array:
  []
);

// as last step, convert the sets into plain arrays:
final.forEach(e => e.values = [...e.values]);

// what did we get?
console.log(final);

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