如果对象的其他值相同，则 JavaScript SUM 对象值

Question

我对 JS 高数组方法很陌生，我有一个包含成本类别和值的对象数组，如下所示:

[{category: "Bars", amount: 31231},
{category: "Transport", amount: 1297},
{category: "Utilities", amount: 12300},
{category: "Bars", amount: 2000},
{category: "Transport", amount: 2500},
{category: "Education", amount: 21321}]

我的目标是减少这个数组并对“金额”值求和，如下所示:

[{category: "Bars", amount: 33231},  //31231+2000
{category: "Transport", amount: 3797}, //1297+2500
{category: "Utilities", amount: 12300},
{category: "Education", amount: 21321}]

我尝试了reduce()和forEach()，但我无法真正找到解决问题的方法。谢谢!

Answer 1

您应该使用reduce方法来执行此操作，因此您将使用项目迭代数组，并且对于每个项目，您将询问该类别是否不存在于 newObject 中。然后用0值初始化，然后求和。

var objects = [{category: "Bars", amount: 31231},
{category: "Transport", amount: 1297},
{category: "Utilities", amount: 12300},
{category: "Bars", amount: 2000},
{category: "Transport", amount: 2500},
{category: "Education", amount: 21321}];

var newObjectsMerged = objects.reduce((object, item) => {
  var category = item.category;
  var amount = item.amount;
  if (!object.hasOwnProperty(category)) {
    object[category] = 0;
  }
  
  object[category] += amount;
  return object;
}, {});

console.log("newObjectsMerged", newObjectsMerged);