如何在JavaScript中的JSON数组中获取重复的对象 [英] How to get repeated objects in json array in javascript

问题描述

我有一个像这样的JSON数组:

I have a JSON array like this :

var data = [
      {title: "HH02"},
      {title: "HH03"},
      {title: "HH04"},
      {title: "HH02"},
      {title: "HH07"},
      {title: "HH08"},
      {title: "HH08"},
      {title: "HH10"},
      {title: "HH02"},
      {title: "HH11"}
]

首先，我想像这样在JSON数组中获取重复的对象:

First I would like to get repeated objects in JSON array like this:

var output = [
     {title: "HH02" },
     {title: "HH08" },
]

然后我想获取所有重复的对象以及它们在这样的另一个JSON数组中重复多少次

Then I would like to get all repeated objects and how many times they are repeated in another JSON array like this

var output = [
     {title: "HH02" , repeat: 3},
     {title: "HH08" , repeat: 2},
]

我尝试这样做，但是效果不佳:

I tried doing this, but it didn't work well:

data.map(v => v.title).sort().sort((a, b) => {
                    if (a === b) output.push(a);
                })

推荐答案

您可以使用减少，过滤和映射

• 首先按 title 将所有值分组，然后在其中重复
• 过滤标题，该标题出现一次或少于一次，然后出现一次(排除它们)
• 映射它们以获得所需的输出

• Group all the values by title first, count there repetition
• Filter the titles which appears once or less then once ( exclude them )
• map them to get desired output

var data = [{title: "HH02"},{title: "HH03"},{title: "HH04"},{title: "HH02"},{title: "HH07"},{title: "HH08"},{title: "HH08"},{title: "HH10"},{title: "HH02"},{title: "HH11"}]

let final = [...data.reduce((op, inp) => {
  let title = inp.title
  op.set(title, (op.get(title) || 0) + 1)
  return op
}, new Map()).entries()].filter(([_,repeat]) => repeat > 1).map(([title, repeat]) => ({
  title,
  repeat
}))

console.log(final)

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