JavaScript 创建对象结构数组

Question

Here is my problem:

I have a JSON structure as below

[{
    "groupid": 29,
    "percentage": 14
}, {
    "groupid": 29,
    "percentage": 22
}, {
    "groupid": 59,
    "percentage": 66,
}]

and i need to convert that into as below using Javascript.

{
    "29": [14, 22],
    "59": [66]
}

Answer 1

reduce the input into an object. On each iteration, create an array at the groupid key in the accumulator object if it doesn't exist yet, and then push to the array:

 const input = [{ "groupid": 29, "percentage": 14 }, { "groupid": 29, "percentage": 22 }, { "groupid": 59, "percentage": 66, }]; const output = input.reduce((a, { groupid, percentage }) => { if (!a[groupid]) a[groupid] = []; a[groupid].push(percentage); return a; }, {}); console.log(output);