json数组把相同key 值合并，value相加

Question

数据如下var arr = [{name: "上海", value: 1},{name: "上海", value: 2},{name: "北京", value: 3},{name: "杭州", value: 2}]想要得到的json数据arr = [{name: "上海", value: 3},{name: "北京", value: 3},{name: "杭州", value: 2}]

Answer 1

function trans (arr) {

  let obj = {}

  let result = []

  arr.forEach(({name, value}) => {

    let cur = obj[name]

    if (cur) {

      let index = cur.index

      result[index].value += value

    } else {

      let index = result.length

      obj[name] = {

        name,

        index

      }

      result.push({name, value})

    }

  })

  return result

}

var arr = [{name: "上海", value: 1},{name: "上海", value: 2},{name: "北京", value: 3},{name: "杭州", value: 2}]

trans(arr)

Answer 2

使用循环