如何编写一个 Switch 语句。
JavaScript Switch 语句
如果希望选择执行若干代码块中的一个，你可以使用 switch 语句：
语法：
switch(n)
{
case 1:
执行代码块 1
break
case 2:
执行代码块 2
break
default:
如果n即不是1也不是2，则执行此代码
}
工作原理：switch 后面的 (n) 可以是表达式，也可以（并通常）是变量。然后表达式中的值会与 case 中的数字作比较，如果与某个 case 相匹配，那么其后的代码就会被执行。break 的作用是防止代码自动执行到下一行
<html>
<SCRIPT LANGUAGE='JavaScript'>
<!--
var color = "green";
switch (color)
{
case "red":
document.write("The car is red.");
break;
case "blue":
document.write("The car is blue.");
break;
case "green":
document.write("The car is green.");
break;
default:
document.write("The car is purple.");
}
//-->
</SCRIPT>
</html>
swicth break
<html>
<head>
<title>A Simple Page</title>
<script language="JavaScript">
<!--
var yourchoice;
yourchoice = prompt("Choose a number between 1 and 4", "1, 2, 3 or 4")
switch (yourchoice)
{
case "1":
alert("You typed in a 1");
break;
case "2":
alert("You typed in a 2");
break;
case "3":
alert("You typed in a 3");
break;
case "4":
alert("You typed in a 4");
break;
default:
alert("You didn't type in a number between 1 and 4");
break;
}
// -->
</script>
</head>
<body></body>
</html>
接着看
<script language="JavaScript">
<!--
var yourchoice;
yourchoice = confirm("Are you at your computer now?")
switch (yourchoice)
{
case true:
alert("true");
break;
case false:
alert("false");
break;
}
// -->
</script>