JavaScript 学习笔记之语句(3)

  switch ("hello world") {
             case "hello" + " world":
                 alert("Greeting was found.");
                 break;
             case "goodbye":
                 alert("Closing was found.");
                 break;
             default:
                 alert("Unexpected message was found.");
         }

复制代码 代码如下:

         var num = 25;
         switch (true) {
             case num < 0:
                 alert("Less than 0.");
                 break;
             case num >= 0 && num <= 10:
                 alert("Between 0 and 10.");
                 break;
             case num > 10 && num <= 20:
                 alert("Between 10 and 20.");
                 break;
             default:
                 alert("More than 20.");
         }

switch语句在比较时使用的是全等操作符比较，因此不会发生类型转换。

练习：

复制代码 代码如下:

 <script type="text/javascript">
         var count = 10;
         for (var i=0; i < count; i++){
             alert(i);
         }
         alert(i);   //输出什么？
     </script>

for(;;){
    alert("2");//输出多少次2？
}