按类别计算数组小计[重复]

Question

我有一个数组：

const expenses = [
        { key: '1', sum: '100', category: 'car' },
        { key: '2', sum: '200', category: 'food'},
        { key: '3', sum: '300', category: 'furniture'},
        { key: '4', sum: '400', category: 'food'},
        { key: '5', sum: '700', category: 'car' },
    ]

如何获得具有特定类别总数的新数组或对象？ 喜欢

newArray = [
{category: 'car' totalSum:800},
{category: 'food' totalSum:600},
{category: 'furniture' totalSum:300}
]

感谢您的任何建议。

Answer 1

使用Array.prototype.reduce():

const expenses = [{key:'1',sum:'100',category:'car'},{key:'2',sum:'200',category:'food'},{key:'3',sum:'300',category:'furniture'},{key:'4',sum:'400',category:'food'},{key:'5',sum:'700',category:'car'},],
    
      result = Object.values(expenses.reduce((r, {category, sum}) =>
        (r[category] = {category, totalSum: (r[category]?.totalSum || 0)+ +sum}, r), {}))
        
console.log(result)

.as-console-wrapper{min-height:100%;}