Introduction

Anyone who has done some work with JavaScript knows it can be very frustrating. Often you have to use:

Alert("I am here"); type of code to debug it. Visual Studio and IE (Internet Explorer) have the ability to debug
JavaScript code, including setting break points in your JavaScript.

Background

When I started working in .NET, I was a VB.NET Windows programmer. When I started to use ASP.NET, the need to use JavaScript started to come up. It was easy for me to make mistakes in my JavaScript since it is a C based language, so there was a real need to have the ability to debug my JavaScript code. I don’t think I would have ever ventured into the JavaScript world without being able to
debug  it in Visual Studio.

Setup

In IE you have to enable script debug ging. Go to Tools, then Internet Options. Click on the Advanced Tab. Un-check disable script

debugging (Internet Explorer). It is checked by default.

NOTE

you will find with script debug ging enabled that many Internet sites have lots of JavaScript problems.


So I would suggest only turning this on when you want to debug
your JavaScript otherwise you will be bothered by IE asking you if you want to debug

other peoples bad JavaScript.

Once you have this set, a new option is available in your View menu. If you click on View there is now a script

debugger option. If you are using IE 7 you will need to click on Tools, then Menu bar to see the View menu item.

So at this point in Visual Studio, if you set your web project / web site to debug

mode and run it, you can debug  your JavaScript.

Under View/Script

Debugger there are two options. The first is Open.

This will open the HTML/JavaScript in Visual Studio and allow you to set break points in your JavaScript.

The other option is Break at next statement which does just what it says. When the next JavaScript gets run, you will go into Visual Studio and it will break on the first JavaScript line.

Once you are in the Visual Studio

debugger, you can use all of the normal tools you have to investigate variables etc. to help with the

debugging of the JavaScript code.

Conclusion

Debugging JavaScript has really helped me to find all the small problems and bugs that are so easy to create when writing JavaScript code.

I hope this article helps you in your JavaScript debugging.