Javascript debugging in Microsoft IE

HOW-TO: Debug JavaScript in Internet Explorer

It seems that best tool for debugging JavaScript on Internet Explorer is the Microsoft Script Editor, a free component of Microsoft Office XP/2003. There are other options - Microsoft Visual Studio .Net, which pretty expensive if all you need is JavaScript debugging for IE.

• Turn on debugging in IE

Go to tools->internet options->advanced. Make sure that “Disable Script Debugging (other)” and “Disable Script Debugging (Internet Explorer) are NOT checked.

• Get Microsoft Script Editor

Restart IE, if you see in view->Script debugger, no other installations are required, otherwise go to Microsoft download page and download Microsoft Script Debugger(link) and restart IE again.
Now check again view->Script debugger, if you see that, then you have Script Editor installed. Congratulations! Otherwise consider to change your professional area :)

• Using Script Debugger

An easiest way to launch the editor from IE (rather than launching it as a stand-alone application). One way to debug is to use IE View->Script Debugger->Break at next statement.

This causes the debugger to activate the next time any JavaScript executes. If you then select “step into code” (F11) the javascript file that contains the code will load automatically.

Alternately, you can put a line like this in your Javascript code.

debugger;

It will create a breakpoints automatically, if this breakpoint gets hit, your debugger will launch. You will see a message that says "An exception 'runtime error' has occurred in script. Possible Debuggers:".

• Usage

When you’re done debugging don't forget to clean all breakpoints, otherwise IE (and possibly the entire operating system) will hang. Then shut down the debugger.

Debugger short keys:
- Run: F5
- Stop debugging: Shift F5
- Step into: F8
- Clear all breakponts: Ctrl+Shift+F9 - Toggle breakpoint: F9 - Step over: Shift+F8
- Step out: Ctrl+Shift+F8

Worth to mention that besides 'Call stack' window with script stack information and 'Running documents', debugger has 'Command window', where you could run functions and see data in a different program variables.



Mozilla's JavaScript Debugger:

http://www.hacksrus.com/~ginda/venkman/
https://addons.mozilla.org/en-US/firefox/addon/216

FireBug:

https://addons.mozilla.org/en-US/firefox/addon/1843

Debugging javascript in Google Chrome:

http://www.alexatnet.com/node/180