throw 语句创建自定义错误
try 语句测试代码块的错误
catch 语句处理错误
<!DOCTYPE html>
<html>
<head>
<title>17th_test</title>
<meta charset="gb2312">
</head>
<body>
<h1>请输出一个 5 到 10 之间的数字:</h1>
<input id="num" type="text" />
<button type="button" οnclick="myFunction()">测试输入</button>
<p id="result"></p>
<script>
function myFunction()
{
var res = document.getElementById("result");
var data = document.getElementById("num").value;
try
{
if(data == "")
throw "不能为空，重新输入";
if(isNaN(data)) //没有else if，只能用if
throw "不是数字，重新输入";
data = Number(data);
if(data < 5)
throw "错误：太小";
if(data > 10)
throw "错误：太大";
else
res.innerHTML = "正确";
}
catch(err)
{
res.innerHTML = err;
}
}
</script>
</body>
</html>output：
