reactjs - 计算嵌套对象数组中的键

Question

有一个长度为 4 的数组。这个长度总是动态的。“出席”是这个对象数组的键之一。这个“出席”也是一个对象数组。

现在我的查询是：当'Make'值为'1'时，如何从'attendance'数组中计算（总）'Make'键。

数组结构图在这里：

请帮帮我。

提前致谢。

标签： reactjs

Answer 1

给定数据：

[
  {
    attendance: [
      { Make: "1", Model: "0", Year: "0", Present: "present" },
      { Make: "2", Model: "1", Year: "1", Absent: "absent" }
    ],
    "course-name": "OS",
    id: 61
  },
  {
    attendance: [
      { Make: "1", Model: "0", Year: "0", Absent: "absent" },
      { Make: "2", Model: "1", Year: "1", Present: "present" }
    ],
    "course-name": "OS",
    id: 62
  },
  {
    attendance: [
      { Make: "1", Model: "0", Year: "0" },
      { Make: "2", Model: "1", Year: "1" }
    ],
    "course-name": "",
    id: 63
  },
  {
    attendance: [
      { Make: "1", Model: "0", Year: "0" },
      { Make: "2", Model: "1", Year: "1" }
    ],
    "course-name": "",
    id: 64
  }
];

您可以将数组减少为总数，检查每个元素的attendance数组是否包含一些Make属性等于 的元素"1"。

data.reduce(
  (total, current) => total + current.attendance.some((el) => el.Make === "1"),
  0
);

const data = [
  {
    attendance: [
      { Make: "1", Model: "0", Year: "0", Present: "present" },
      { Make: "2", Model: "1", Year: "1", Absent: "absent" }
    ],
    "course-name": "OS",
    id: 61
  },
  {
    attendance: [
      { Make: "1", Model: "0", Year: "0", Absent: "absent" },
      { Make: "2", Model: "1", Year: "1", Present: "present" }
    ],
    "course-name": "OS",
    id: 62
  },
  {
    attendance: [
      { Make: "1", Model: "0", Year: "0" },
      { Make: "2", Model: "1", Year: "1" }
    ],
    "course-name": "",
    id: 63
  },
  {
    attendance: [
      { Make: "1", Model: "0", Year: "0" },
      { Make: "2", Model: "1", Year: "1" }
    ],
    "course-name": "",
    id: 64
  }
];

const make1Count = data.reduce(
  (total, current) => total + current.attendance.some((el) => el.Make === "1"),
  0
);

console.log(make1Count);