在 JS 中查找累加器的属性

debugcn 发表于 Dev

用户7319004

我正在运行这个累加器，它工作得很好，但我发现在同一个对象中添加一些属性具有挑战性：

  let expenseCategories = expenseObj.reduce((acc, obj) => {
    let category = obj['category'];
    // let amount = obj['amount'];
    if (category in acc) {
      acc[category] += 1;
    } else {
      acc[category] = 1;
    }
    return acc;
  }, {});

{交通：2，食物：1，衣服：1，账单：2，乐趣：1，……}

我的初始对象还包含交易金额

{amount: 10, category: "Transportation", date: 20190510, expense: true, ...
{amount: 20, category: "Drinks", date: 20190510, expense: true, ...
{amount: 30, category: "Bills", date: 20190510, expense: true, ...
{amount: 40, category: "Bills", date: 20190510, expense: true, ...

我的目标是计算每个类别的总和，bills如上例所示，为 70。

我希望添加此信息以显示一些图表，预期的数组如下所示：

0: {name: "Transportation", value: 2, total: 123}
1: {name: "Food", value: 1, total: 456}
2: {name: "Clothes", value: 1, total: 789}

这是我对我已有的正确数据的尝试：

let outExpense = Object.entries(expenseCategories).map(([name, value]) => ({ name, value }));

这应该是动态的，因为在运行代码之前我不知道类别。这些是用户输入。请指教。谢谢

你

您正在计算每个的出现次数category。你需要稍微改变你的实现。您可以在输出数组中创建您需要的对象作为值，而不是创建一个数字作为值。然后，只需Object.values()在累加器对象上使用即可获取分组值数组

const expenseObj = [{amount: 10, category: "Transportation", date: 20190510, expense: true},
{amount: 20, category: "Drinks", date: 20190510, expense: true},
{amount: 30, category: "Bills", date: 20190510, expense: true},
{amount: 40, category: "Bills", date: 20190510, expense: true}]

let groupCategories = expenseObj.reduce((acc, obj) => {
  let { category, amount } = obj;
  
  if (category in acc) {
    acc[category].value++;    
    acc[category].total += amount;
  } else {
    acc[category] = { name: category, value: 1, total: amount };
  }
  return acc;
}, {});

console.log(Object.values(groupCategories))

这就是累加器在更改后的样子。如果当前对象category已存在于累加器中，则增加value和total。否则，添加categoryas 键和一个新对象作为它的值

{
  "Transportation": {
    "name": "Transportation",
    "value": 1,
    "total": 10
  },
  "Drinks": {
    "name": "Drinks",
    "value": 1,
    "total": 20
  },
  "Bills": {
    "name": "Bills",
    "value": 2,
    "total": 70
  }
}

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