如何在对象数组中查找元素的所有出现并在 Javascript 中求和它们的相应值

Question

我有一个对象数组，如下所示：

[
  { code: "a", value: 20 },
  { code: "b", value: 20 },
  { code: "c", value: 20 },
  { code: "a", value: 20 },
  { code: "b", value: 20 },
]

我想通过为所有唯一代码添加值来减少它

[
  { code: "a", value: 40 },
  { code: "b", value: 40 },
  { code: "c", value: 20 },
]

Answer 1

您可以使用函数Array.prototype.reduce按code对对象进行分组，使用函数Object.values来提取分组的对象。

 let arr = [{code : 'a', value :20},{code : 'b', value :20},{code : 'c', value :20},{code : 'a',value :20},{code : 'b', value :20}], result = Object.values(arr.reduce((a, {code, value}) => { (a[code] || (a[code] = {code, value: 0})).value += value; return a; }, Object.create(null))); console.log(result);

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Answer 2

您可以使用reduce来存储代码值查找对象，并使用Object.entries()遍历该对象，然后进行操作以获取最终值

 const arr = [ { code: "a", value: 20 }, { code: "b", value: 20 }, { code: "c", value: 20 }, { code: "a", value: 20 }, { code: "b", value: 20 }, ] const codeValueMapping = arr.reduce((acc, el) => { if (acc[el.code]) { acc[el.code] += el.value } else { acc[el.code] = el.value } return acc }, {}) const res = Object.entries(codeValueMapping).map(([code, value]) => ({ code, value, })) console.log(res)

Answer 3

一种解决方案是在 ECMA 6 中使用 set

[...new Set(YOUR_ARRAY.map(JSON.stringify))].map(JSON.parse)