JS+switch语句用法

switch (expression) {
  case value1:
    // 当 expression 等于 value1 时执行的代码
    break;
  case value2:
    // 当 expression 等于 value2 时执行的代码
    break;
  // ...
  default:
    // 当 expression 不匹配任何 case 时执行的代码
}

let day = 3;
let dayName;

switch (day) {
  case 1:
    dayName = 'Monday';
    break;
  case 2:
    dayName = 'Tuesday';
    break;
  case 3:
    dayName = 'Wednesday';
    break;
  // ...
  case 7:
    dayName = 'Sunday';
    break;
  default:
    dayName = 'Invalid day';
}

console.log(dayName); // 输出: Wednesday

let day = 3;
let dayName;

switch (day) {
  case 1:
    dayName = 'Monday';
    break;
  case 2:
    dayName = 'Tuesday';
    // 忘记写 break
  case 3:
    dayName = 'Wednesday';
    break;
  // ...
}

console.log(dayName); // 输出: Wednesday，而不是预期的 Tuesday

let day = 8;
let dayName;

switch (day) {
  case 1:
    dayName = 'Monday';
    break;
  // ...
  default:
    dayName = 'Invalid day';
}

console.log(dayName); // 输出: Invalid day