javascript - 如何在Java Script中计算Plaid API事务数组的值总和？

为潜在的愚蠢问题表示歉意-我是编码/ JavaScript的新手。

我正在使用Plaid's沙箱环境在沙箱环境中提取事务数据。现在，我将以下定义为transactionData：

    let transactionsData = [];
transactions.forEach(function(account) {
  account.transactions.forEach(function(transaction) {
    transactionsData.push({
      account: account.accountName,
      date: transaction.date,
      category: transaction.category[0],
      name: transaction.name,
      amount: transaction.amount
    });
  });
});

我可以成功地在material table中逐行呈现单个交易，如下所示：

    const transactionsColumns = [
  { title: "Account", field: "account" },
  { title: "Date", field: "date", type: "date", defaultSort: "desc" },
  { title: "Name", field: "name" },
  { title: "Amount", field: "amount", type: "numeric" },
  { title: "Category", field: "category" }
];

          <MaterialTable
            columns={transactionsColumns}
            data={transactionsData}
            }}

我知道这必须非常简单，但是我要做的就是将transactionsData求和并在页面的其他位置呈现该求和的值。如果我写transactionsData.length，我可以很容易地接收到交易计数。我尝试了以下类似的语法，但没有发现它起作用：

array.reduce(function(total, currentValue, currentIndex, arr), initialValue)

任何帮助将非常感激。

最佳答案

总计，使用Array.prototype.reduce：

const transformed = [{"account":"Navy Federal Credit Union","date":"2020-01-01","category":"Travel","name":"United Airlines","amount":500},{"account":"Navy Federal Credit Union","date":"2019-12-30","category":"Travel","name":"Uber 072515 SF**POOL**","amount":6.33},{"account":"Navy Federal Credit Union","date":"2019-12-27","category":"Food and Drink","name":"Tectra Inc","amount":500}]

const unrounded = transformed.reduce(
  (acc, { amount }) => acc + amount,
  0
);

const roundCents = amount => Math.round(amount * 100) / 100;

const total = roundCents(unrounded);

console.log(total);

上面的普通版本，没有破坏性：

const transformed = [{"account":"Navy Federal Credit Union","date":"2020-01-01","category":"Travel","name":"United Airlines","amount":500},{"account":"Navy Federal Credit Union","date":"2019-12-30","category":"Travel","name":"Uber 072515 SF**POOL**","amount":6.33},{"account":"Navy Federal Credit Union","date":"2019-12-27","category":"Food and Drink","name":"Tectra Inc","amount":500}]

const unrounded = transformed.reduce(
  (acc, transaction) => acc + transaction.amount,
  0
);

const roundCents = amount => Math.round(amount * 100) / 100;

const total = roundCents(unrounded);

console.log(total);

以下是使用transactionsData和Array.prototype.flatMap而不是Array.prototype.map转换forEach的方法：

const transactionsData = [{ accountName: 'a1', transactions: [{ date: '2020', category: ['c1'], name: 'n1', amount: 100 }, { date: '2020', category: ['c2'], name: 'n2', amount: 100 }]}, { accountName: 'a2', transactions: [{ date: '2020', category: ['c3'], name: 'n3', amount: 100 }, { date: '2020', category: ['c4'], name: 'n4', amount: 100 }]}]

const transformed = transactionsData.flatMap(({ accountName, transactions }) =>
  transactions.map(({ date, category, name, amount }) => ({
      account: accountName,
      date,
      category: category[0],
      name,
      amount
    })
  )
);

console.log(transformed)

再一次，是一个简单的版本，没有破坏：

const transactionsData = [{ accountName: 'a1', transactions: [{ date: '2020', category: ['c1'], name: 'n1', amount: 100 }, { date: '2020', category: ['c2'], name: 'n2', amount: 100 }]}, { accountName: 'a2', transactions: [{ date: '2020', category: ['c3'], name: 'n3', amount: 100 }, { date: '2020', category: ['c4'], name: 'n4', amount: 100 }]}]

const transformed = transactionsData.flatMap(account =>
  account.transactions.map(transaction => ({
      account: account.accountName,
      date: transaction.date,
      category: transaction.category[0],
      name: transaction.name,
      amount: transaction.amount
    })
  )
);

console.log(transformed)

Array.prototype.map是要从现有数组创建新数组时使用的正确方法，而Array.prototype.flatMap是需要展平数组且map会生成嵌套数组时使用的正确方法。