一 语法
try {
tryCode - 尝试执行代码块
}
catch(err) {
catchCode - 捕获错误的代码块
}
finally {
finallyCode - 无论 try / catch 结果如何都会执行的代码块
}二 try ... catch
</head>
<body>
<p>请输入 5 和 10 之间的一个数:</p>
<input id="demo" type="text">
<button type="button" onclick="myFunction()">检测输入</button>
<p id="message"></p>
<script>
function myFunction() {
var message, x;
message = document.getElementById("message");
message.innerHTML = "";
x = document.getElementById("demo").value;
try {
if(x == "") throw "为空";
if(isNaN(x)) throw "不是一个数字";
if(x > 10) throw "太大了";
if(x < 5) throw "太小了";
}
catch(err) {
message.innerHTML = "输入的值 " + err;
}
}
</script>
</body>
</html>三 try ... finally
<input id="demo" type="text">
<button type="button" onclick="myFunction()">检测输入</button>
<p id="message"></p>
<script>
function myFunction() {
var message, x;
message = document.getElementById("message");
message.innerHTML = "";
x = document.getElementById("demo").value;
try {
if(x == "") throw "为空";
if(isNaN(x)) throw "不是一个数字";
if(x > 10) throw "太大";
if(x < 5) throw "太小";
}
catch(err) {
message.innerHTML = "输入的值 " + err;
}
finally {
document.getElementById("demo").value = 1000;
}
}
</script>
</body>
</html>