Not able to debug javascript syntax error

I was working on a Facebook application. I made some changes to the page as well as javascript controlling behavior of the page. Fires up the application and I kept getting javascript error dialog popup. And everytime I will hit "Yes" to allow debugging of error, the code will not goto debugger and will move on. I tried Firebig, IE Developer toolbar etc. Nothing will show me the error. Then I started going back to all changes that I checked. Right on the HTML markup i noticed that I added a call to a javascript function on a click event. And noticed that I missed closing quotes on a javascript function call for a click event. After I added closing quotes error went away.

So if you run into situation like this, do look at javascript syntax in mark up as well. Thats where the problem may be. For all javascript file syntax errors, tools like firebug etc. can point you to right location most of the time.