拆分函数

拆分功能太多的函数

下面是一个打印账单的程序：

function printBill(data = []) {
  // 汇总数据
  const total = {};
  data.forEach((item) => {
    if (total[item.department] === undefined) {
      total[item.department] = 0;
    }

    total[item.department] += item.value;
  });
  // 打印汇总后的数据
  const keys = Object.keys(total);
  keys.forEach((key) => {
    console.log(`${key} 部门：${total[key]}`);
  });
}

printBill([
  {
    department: "销售部",
    value: 89,
  },
  {
    department: "后勤部",
    value: 132,
  },
  {
    department: "财务部",
    value: 78,
  },
  {
    department: "总经办",
    value: 90,
  },
  {
    department: "后勤部",
    value: 56,
  },
  {
    department: "总经办",
    value: 120,
  },
]);

可以看到这个 printBill() 函数实际上包含有两个功能：汇总和打印。我们可以把汇总数据的代码提取出来，封装成一个函数。这样 printBill() 函数就只需要关注打印功能了。

function printBill(data = []) {
  const total = calculateBillData(data);
  const keys = Object.keys(total);
  keys.forEach((key) => {
    console.log(`${key} 部门：${total[key]}`);
  });
}

function calculateBillData(data) {
  const total = {};
  data.forEach((item) => {
    if (total[item.department] === undefined) {
      total[item.department] = 0;
    }

    total[item.department] += item.value;
  });

  return total;
}