javascript - 如何按重复值拆分数组？

Question

我有一个对象数组，我必须按 index 属性上的重复值拆分它。对于像下一个这样的对象示例数组:

[
  {index: 0, value: 3},
  {index: 0, value: 3},
  {index: 0, value: 3},
  {index: 1, value: 3},
  {index: 1, value: 3},
  {index: 2, value: 3},
  {index: 2, value: 3}
]

预期的结果应该是:

{
  0: [
    {index: 0, value: 3},
    {index: 0, value: 3},
    {index: 0, value: 3}
  ],
  1: [
    {index: 1, value: 3},
    {index: 1, value: 3}          
  ],
  2: [
    {index: 2, value: 3},
    {index: 2, value: 3}
  ]
}

Answer 1

这里有一个使用 reduce() 的解决方案和 Object.assign() :

const input = [
  {index: 0, value: 3},
  {index: 0, value: 3},
  {index: 0, value: 3},
  {index: 1, value: 3},
  {index: 1, value: 3},
  {index: 2, value: 3},
  {index: 2, value: 3},
  {index: 0, value: 3}
];

let obj = input.reduce((res, curr) =>
{
    if (res[curr.index])
        res[curr.index].push(curr);
    else
        Object.assign(res, {[curr.index]: [curr]});

    return res;
}, {});

console.log(obj);

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前面的示例将对具有相同 index 属性的所有对象进行分组。但是，如果您希望通过具有相同 indexes 的条纹来分隔对象，您可以这样做:

const input = [
  {index: 0, value: 3},
  {index: 0, value: 3},
  {index: 0, value: 3},
  {index: 1, value: 3},
  {index: 1, value: 3},
  {index: 2, value: 3},
  {index: 2, value: 3},
  {index: 0, value: 3},
  {index: 0, value: 3},
  {index: 0, value: 3},
  {index: 2, value: 3},
  {index: 2, value: 3}
];

let obj = input.reduce((res, curr) =>
{
    if (curr.index === res.last)
    {
        res.r[res.idx - 1].push(curr);
        return res;
    }

    Object.assign(res.r, {[res.idx]: [curr]});
    res.last = curr.index;
    res.idx++;
    return res;

}, {r: {}, idx: 0, last: null});

console.log(obj.r);

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