如何使用JavaScript reduce按日期统计回答数及total值

需求说明 #

需要基于给定的回答数组，按日期维度做分组统计，每个日期分组需返回三个统计值：

• yes：该日期下回答为yes的条数
• no：该日期下回答为no的条数
• total：该日期下回答总条数

期望单组输出格式如下：

"2022-01-03": {
    "yes": 1,
    "no": 2,
    "total": 3
}

原有代码说明 #

现有reduce逻辑已经完成了yes、no两个字段的计数，仅缺少total字段的初始化和累加逻辑，原有代码如下：

const array = [
  { date: '2022-01-03', answer: 'yes' },
  { date: '2022-01-03', answer: 'no' },
  { date: '2022-01-03', answer: 'no' },
  { date: '2022-01-04', answer: 'yes' },
  { date: '2022-01-04', answer: 'yes' },
  { date: '2022-01-05', answer: 'yes' },
  { date: '2022-01-05', answer: 'yes' },
  { date: '2022-01-05', answer: 'yes' },
  { date: '2022-01-05', answer: 'no' },
]

const result = array.reduce((acc, curr) => {
  if (!acc[curr.date]) {
    acc[curr.date] = { yes: 0, no: 0 }
  }
  acc[curr.date][curr.answer]++;
  return acc;
}, {});

console.log(result)

修改后完整代码 #

仅需两处调整即可满足需求：

1. 初始化日期分组对象时，新增total字段并设置初始值为0
2. 每次遍历到对应日期的回答时，同步对total字段做自增

const array = [
  { date: '2022-01-03', answer: 'yes' },
  { date: '2022-01-03', answer: 'no' },
  { date: '2022-01-03', answer: 'no' },
  { date: '2022-01-04', answer: 'yes' },
  { date: '2022-01-04', answer: 'yes' },
  { date: '2022-01-05', answer: 'yes' },
  { date: '2022-01-05', answer: 'yes' },
  { date: '2022-01-05', answer: 'yes' },
  { date: '2022-01-05', answer: 'no' },
]

const result = array.reduce((acc, curr) => {
  if (!acc[curr.date]) {
    acc[curr.date] = { yes: 0, no: 0, total: 0 }
  }
  acc[curr.date][curr.answer]++;
  acc[curr.date].total++;
  return acc;
}, {});

console.log(result)

运行上述代码后，输出结果完全匹配需求格式，各日期统计值准确。

内容的提问来源于stack exchange，提问作者Legion