js switch语句的嵌套使用技巧

在 JavaScript 中，可以在一个 switch 语句内部嵌套另一个 switch 语句。这种嵌套的使用技巧可以让你的代码更加模块化和易于维护。以下是一些建议和技巧：

1. 将相关的逻辑放在一起：嵌套 switch 语句可以让你将与特定条件相关的逻辑组合在一起，使代码更易于阅读和理解。

2. 使用有意义的命名：为每个 case 和嵌套的 switch 语句提供有意义的名称，以便于理解代码的意图。

3. 保持简洁：尽量避免过深的嵌套，以保持代码的可读性。如果嵌套层数过多，可以考虑将部分逻辑提取到函数中。

4. 使用默认情况：在每个 case 和嵌套的 switch 语句中添加默认情况，以处理可能未覆盖到的值。

下面是一个嵌套 switch 语句的示例：

function getDayOfWeek(dayNumber) {
  let dayOfWeek;

  switch (dayNumber) {
    case 0:
      dayOfWeek = 'Sunday';
      break;
    case 1:
      dayOfWeek = 'Monday';
      break;
    case 2:
      dayOfWeek = 'Tuesday';
      break;
    case 3:
      dayOfWeek = 'Wednesday';
      break;
    case 4:
      dayOfWeek = 'Thursday';
      break;
    case 5:
      dayOfWeek = 'Friday';
      break;
    case 6:
      dayOfWeek = 'Saturday';
      break;
    default:
      dayOfWeek = 'Invalid day number';
  }

  return dayOfWeek;
}

function getWeekInfo(weekNumber) {
  let weekInfo;

  switch (weekNumber) {
    case 1:
      weekInfo = 'Week 1';
      break;
    case 2:
      weekInfo = 'Week 2';
      break;
    case 3:
      weekInfo = 'Week 3';
      break;
    case 4:
      weekInfo = 'Week 4';
      break;
    default:
      weekInfo = 'Invalid week number';
  }

  return weekInfo;
}

function getDayInfo(dayNumber, weekNumber) {
  const dayOfWeek = getDayOfWeek(dayNumber);
  const weekInfo = getWeekInfo(weekNumber);

  switch (dayOfWeek) {
    case 'Sunday':
      return `Today is ${dayOfWeek}, ${weekInfo}.`;
    case 'Monday':
      return `Today is ${dayOfWeek}, ${weekInfo}.`;
    case 'Tuesday':
      return `Today is ${dayOfWeek}, ${weekInfo}.`;
    case 'Wednesday':
      return `Today is ${dayOfWeek}, ${weekInfo}.`;
    case 'Thursday':
      return `Today is ${dayOfWeek}, ${weekInfo}.`;
    case 'Friday':
      return `Today is ${dayOfWeek}, ${weekInfo}.`;
    case 'Saturday':
      return `Today is ${dayOfWeek}, ${weekInfo}.`;
    default:
      return `Today is ${dayOfWeek}, ${weekInfo}.`;
  }
}

console.log(getDayInfo(3, 2)); // Output: Today is Wednesday, Week 2.

在这个示例中，我们使用了嵌套的 switch 语句来根据输入的星期几和周数获取对应的星期信息。这种结构使得代码更加模块化和易于维护。