javascript - 我如何在javascript中返回两个对象

Question

举个例子
我有两个数组

const tempData = [
          { day: "Mon", temp: 33.6 },
          { day: "Tue", temp: 34.6 },
          { day: "Wed", temp: 33.1 },
          { day: "Fri", temp: 35.6 }
        ];
const coughData = [
          { day: "Mon", count: 2 },
          { day: "Wed", count: 1 },
          { day: "Thur", count: 1 },
          { day: "Fri", count: 3 },
          { day: "Sat", count: 1 }
        ]; 

我需要将这些数组合并为一个，以便如果日期匹配，则计数值添加到该对象，如果不匹配，它将两个对象添加到数组中。
不知道解释是不是不是很清楚但是
预期的结果应该是这样的:

const data = [
          { day: "Mon", temp: 33.6, count: 2 },
          { day: "Tue", temp: 34.6 },
          { day: "Wed", temp: 33.1, count: 1 },
          { day: "Thur", count: 1 },
          { day: "Fri", temp: 35.6, count: 3 },
          { day: "Sat", count: 1 }
        ];

我正在尝试像这样使用 map 函数，但无法理解如果它们不匹配，我该如何返回这两个对象:

const data = tempData.map(temp => {
          coughData.map(cough => {
            if (temp.day === cough.day) {
              return (temp.count = cough.count);
            } else {
              return cough;
            }
          });
          return temp;
        });

Answer 1

您可以先合并数组的对象，然后使用 .reduce() 连同 Map来累积值。 map 可以通过 day 键控属性，这将允许您将相关的对象属性组合在一起。然后您可以使用 Array.from() 将您的 Map 转换回一个对象数组，如下所示:

const tempData = [{ day: "Mon", temp: 33.6 }, { day: "Tue", temp: 34.6 }, { day: "Wed", temp: 33.1 }, { day: "Fri", temp: 35.6 }];
const coughData = [{ day: "Mon", count: 2 }, { day: "Wed", count: 1 }, { day: "Thur", count: 1 }, { day: "Fri", count: 3 }, { day: "Sat", count: 1 }];

const arr = [...tempData, ...coughData];

const result = Array.from(arr.reduce((map, {day, ...rest}) => {
  const seen = map.get(day) || {day};
  return map.set(day, {...seen, ...rest});
}, new Map).values());

console.log(result);