Question

I’m using JScript.NET to write scripts in a C# WinForms application I wrote. It works really well, but I just tried putting some exception handling in a script, and I can’t figure out how to tell what type of exception was thrown from my C# code.

Here’s some example JScript code that throws two different types of CLR exception, and then tries to catch them and tell them apart.

function ErrorTest(name)
{
    try
    {
        if (name.length < 5)
        {
            throw new ArgumentException();
        }else
        {
            throw new InvalidOperationException();
        }
    }catch (e)
    {
        return e.name + " " + (e.number & 0xFFFF) + ": " + e.message;
    }
}

If I call ErrorTest("foo"), then I get back "Error 5022: Value does not fall within the expected range.", and if I call ErrorTest("foobar"), then I get back "Error 5022: Operation is not valid due to the current state of the object."

The name and number properties are identical, the only difference is the message. I don’t want to start writing error handling logic based on the error messages, so is there some way to get at the original exception instead of the JScript Error object?

Answer 1

Use JScript .NET’s type annotation support, like so:

  try { }
  catch (e : ArgumentException) {
    // ...
  }