1 if语句

  1.         var a= prompt("请输入你的年龄");//弹窗显示
  2.         if(a>=18){
  3.             alert("上班")//弹窗显示
  4.         }
  5.         else{
  6.             alert("家里蹲")
  7.         }

2 elseif语句

  1.         var distance = prompt("距离");
  2.         if(distance<=400){
  3.             alert(24);
  4.         }else if(distance<=1000){
  5.             alert(30)
  6.         }else if(distance<=3000){
  7.             alert(40)
  8.         }else if(distance<=5000){
  9.             alert(100)
  10.         }else {
  11.             alert("100+")
  12.         }

3 switch语句

  1. <script>
  2.         var score = prompt("请输入你的分数");
  3.         score = Number(score);
  4.     switch(score){
  5.        case 100:alert("满分");break
  6.        case 90:alert("优");break
  7.        case 80:alert("良");break
  8.        case 60:alert("及格");break
  9.        default:alert("重修")
  10.       }
  11. </script>

4 while循环

  1. <script>
  2.    var age = prompt("");
  3.    while(age<=10,age++){
  4.        console.log(age)
  5.        break
  6.    }
  7. </script>

5 break

  1.         /* break：跳出循环 */
  2.         for(var i = 0;i<=5;i++){
  3.             if(i==3){
  4.                 break;
  5.             }
  6.             console.log(i)
  7.         }

6 continue

  1.         /* continue 继续循环 */
  2.         for(var i = 0;i<=5;i++){
  3.             if(i==3){
  4.                 continue;
  5.             }
  6.             console.log(i)
  7.         }