Exception Handling through JavaScript
Exception handling is an
important concept which is widely used in programming language. Exception
handling is an important approach which is designed to handle unexpected
occurrence of code error in programming language. In other word, Exception
handling is occurrence of unexpected code error due to which the execution of
program may be terminated.
There is a specific way to handle the exception in JavaScript.
Try, catch and finally are used to handle the exception. Try contains those
blocks of code there is probability to occurrence unexpected code error and
when exception is raised then catch block catches that exception and handle that
exception i.e. catch block contains exception handler code.
Here I am giving a small example to how exception handles
within the JavaScript code. Here I am taking two input number1 and number2 and
print division result of these two numbers.
Example: How to handle
exception through the JavaScript
<html>
<head>
<title>Exception Handling</title>
<script type="text/javascript">
function ClickEventResult() {
var num1 = document.getElementById("TextBox1").value;
var num2 = document.getElementById("TextBox2").value;
try {
if (num1 == ""
|| num2 == "")
{
//// throw the
exception when textbox is empty, throw keyword is used for throw user execption
throw "empty";
}
else {
/// calculate
division result
var result;
result = num1 /
num2;
//// result show
with confirm pop up message box
confirm(result);
}
}
catch (Error) {
if (Error == "empty")
{
/// exception
catch when empty throw
alert("Textbox cannot empty:" + Error);
}
else {
//// exception
occured when result calculated
alert(Error);
}
}
}
</script>
</head>
<body>
<form id="form1" runat="server">
<div>
<table style="width: 446px; height: 132px">
<tr>
<td class="style1">
<asp:Label ID="Label1" runat="server" Text="Enter first Number:"></asp:Label>
</td>
<td>
<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server"
ControlToValidate="TextBox1" ErrorMessage="*"></asp:RequiredFieldValidator>
<asp:RangeValidator ID="RangeValidator1" runat="server"
ControlToValidate="TextBox1" ErrorMessage="*" MaximumValue="999999"
MinimumValue="0" Type="Integer"></asp:RangeValidator>
</td>
</tr>
<tr>
<td class="style1">
<asp:Label ID="Label2" runat="server" Text="Enter Second Number:"></asp:Label>
</td>
<td>
<asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>
<asp:RequiredFieldValidator ID="RequiredFieldValidator2" runat="server"
ControlToValidate="TextBox2" ErrorMessage="*"></asp:RequiredFieldValidator>
<asp:RangeValidator ID="RangeValidator2" runat="server"
ControlToValidate="TextBox2" ErrorMessage="*" MaximumValue="999999"
MinimumValue="0" Type="Integer"></asp:RangeValidator>
</td>
</tr>
<tr>
<td class="style1">
</td>
<td>
<%--
ClickEventResult Call the javascript block when button clicked by client--%>
<asp:Button ID="Button2" runat="server" Text="Division" OnClientClick="ClickEventResult();" />
</td>
</tr>
</table>
</div>
</form>
</body>
</html>