switch语句

const expr = 'Papayas';
switch (expr) {
  case 'Oranges':
    console.log('Oranges are $0.59 a pound.');
    break;
  case 'Mangoes':
  case 'Papayas':
    console.log('Mangoes and papayas are $2.79 a pound.');
    // Expected output: "Mangoes and papayas are $2.79 a pound."
    break;
  default:
    console.log(`Sorry, we are out of ${expr}.`);
}

• case valueN 

• 用于匹配 expression 的 case 子句。如果 expression 与给定的 valueN 相匹配，则执行该 case 子句中的语句直到该 switch 语句结束或遇到一个 break 。

• default 

• 一个 default 子句；如果给定，这条子句会在 expression 的值与任一 case 语句均不匹配时执行。

可以进行多个判断

const expr = 'Papayas';
switch (expr) {
  case 'Oranges'||'Mangoes'://多个
    console.log('Oranges are $0.59 a pound.');
    break;
  case 'asass'
  case 'Papayas':
    console.log('Mangoes and papayas are $2.79 a pound.');
    // Expected output: "Mangoes and papayas are $2.79 a pound."
    break;
  default:
    console.log(`Sorry, we are out of ${expr}.`);
}