Debugging JavaScript Code Using VS and IE

Article

We can easily debug C# code using breakpoints but when we want to debug JavaScript code then we need to make some extra effort. I explain in this article step-by-step how to debug JavaScript code defined in a .aspx page using Visual Studio and Internet Explorer so let's see that now.

Step 1 : Create a WebForm

We create a webform that has a JavaScript function called on a button click. Here we have SquareNumber(), a JavaScript function that squares a value that is then inserted in TextBox by the user on a button click and shows the resulting value in an alert box.

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
    <script type ="text/javascript">
        function SquareNumber()
        {
            var number = document.getElementById("<%=txtNumber.ClientID %>").value;
            alert(number +" square is :"+ number*number);
        }
    </script>
</head>
<body>
    <form id="form1" runat="server">
    <div>
    Enter a Number : <asp:TextBox ID="txtNumber" runat="server"></asp:TextBox>
    <asp:Button ID="btnSquare" runat="server" Text="Square" OnClientClick="SquareNumber()" />
    </div>
    </form>
</body>
</html>

Step 2 : Setting in IE to enable debug

Go to "Tools" - "Internet Option"
Go to the "Advanced" tab - "Browsing" then uncheck "Disable Script Debugging" then click "OK".

Step 3 : Insert breakpoint

We insert the breakpoint where the pointer will hit directly.

Step 4 : Run the applications (press the F5 Key)

When we run the application then the following web page is shown and then insert a value into the TextBox.

Click on the "Square" button:

Get the output:

Step 5 : Insert debugger

When we insert the JavaScript debugger then the code will be started from the debugger and will proceed line by line; in this case we don't need to insert a breakpoint. We only need to write debugger in a JavaScript function where we start the debug code.

Press the F10 key to move to the next line.

NOTE : Remove the JavaScript debugger before publishing or releasing a website or web application.