使用 javascript 在 json 中组合对象

Question

Having a JSON in this format:

[{
    name: "A",
    country: "X",
    countryID: "02",
    value: 15
  },
  {
    name: "A",
    country: "Y",
    countryID: "01",
    value: 25
  },
  {
    name: "B",
    country: "X",
    countryID: "02",
    value: 35
  },
  {
    name: "B",
    country: "Y",
    countryID: "01",
    value: 45
  }
]

how can I combine the objects by name , country , and countryID in Javascript to get the following JSON output?

[{
    country: "Y",
    countryID: "01",
    valueA: 25,
    valueB: 45
  },
  {
    country: "X",
    countryID: "02",
    valueA: 15,
    valueB: 35
  }
]

Answer 1

Using Array.prototype.reduce , you can group array items by country and countryID key-value pairs and store the result to the object values of that generated key as follows.

 const input = [{ name: "A", country: "X", countryID: "02", value: 15 }, { name: "A", country: "Y", countryID: "01", value: 25 }, { name: "B", country: "X", countryID: "02", value: 35 }, { name: "B", country: "Y", countryID: "01", value: 45 } ]; const groupBy = input.reduce((acc, cur) => { const key = `${cur.country}_${cur.countryID}`; acc[key] ? acc[key][`value${cur.name}`] = cur.value : acc[key] = { country: cur.country, countryID: cur.countryID, ['value' + cur.name]: cur.value }; return acc; }, {}); const output = Object.values(groupBy); console.log(output);