What is the best Debugger for debugging Javascript code

Happy gold cup weekend everyone !.

Really hope someone can help me with this.


1) I'm developing a web "application" using PHP , HTML and Javascript.

2) Most of the code is written with .php pages

3) Some javascript is written directly in the .php page but most of the complex js  is included by included external .js pages on the .php page using statements  -like echo('<script type="text/javascript" src="'.$Path.$FileName.'.js"></script> '); - to include javascript pages  

4) I have been using Microsoft script debugger 1.0.7 which seems to identify js errors in the js that is written directly into the .php page. HOWEVER whenever the source of the js error is on one of the included js pages the debugger seems to highlight lines of code that have nothing to do with the error.

Can someone please :
1) Most importantly point me to the best Javascript debugger available ?!
2) Or alternatively tell me how to deal with the issue I'm encountering using Microsoft script debugger?

Thanks in advance all for your usual helpfulness.

Regards,

winbiz

And perhaps tell me if they