函数内的开关在Typescript中不能正常工作

switch (expression) {
  case value1:
    // 当expression等于value1时执行的代码块
    break;
  case value2:
    // 当expression等于value2时执行的代码块
    break;
  default:
    // 当expression不等于任何case时执行的代码块
    break;
}

function processFruit(fruit: string) {
  switch (fruit) {
    case 'apple':
      console.log('Selected fruit is apple');
      break;
    case 'banana':
      console.log('Selected fruit is banana');
      break;
    default:
      console.log('Selected fruit is unknown');
      break;
  }
}

processFruit('apple'); // 输出：Selected fruit is apple
processFruit('orange'); // 输出：Selected fruit is unknown