--- a/firefox-devel.rst	Mon May 30 17:36:19 2011 +0300
+++ b/firefox-devel.rst	Tue May 31 16:05:26 2011 +0300
@@ -75,3 +75,36 @@
 * Extension security.
 
   https://developer.mozilla.org/en/Security_best_practices_in_extensions
+
+* Debugin Firefox.
+
+  https://developer.mozilla.org/en/how_to_get_a_stacktrace_with_windbg
+
+* Debugin JavaScript in Firefox.
+
+** Debugging JavaScript in Firefox with Web Console.
+
+'console.log()', 'console.info()', 'console.warn()', 'console.error()'.
+
+  https://developer.mozilla.org/en/Using_the_Web_Console
+
+** Debugging JavaScript in Firefox with Firebug.
+
+With Firebug you can use 'console.log(obj)' for logging. Also output can be grouped with
+console.group("name") to start a new indentation block, and then console.groupEnd().
+
+Same but with different coloring do 'console.debug', 'console.info', 'console.warn', and
+'console.error' functions.
+
+'console.log' can format strings in the great tradition of printf.
+
+'console.trace()' - to print trace.
+
+  http://getfirebug.com/logging
+
+** dump().
+
+Set in 'about:config' 'browser.dom.window.dump.enabled' to 'true'.
+
+All messages go to Web console.
+