Personally, I don't think I'll need a JavaScript debugger. A code completion thing would be great, though, offering global and local variables for function calls, and easy access to functions and variables the user has created, even if they were added to already-existing object classes. Anyway...
What I'd like to see with the next HTMLPad would be a context-menu option, special click, or function key that takes you to the page and line where a certain identifier is defined. In the background, this could actually be a sort of find/grep utility that looks for the function definition or the var keyword (or at least the first occurance of the keyword).
Why do I want this? Because I inherit other people's code, that's why. I have to maintain it and write new stuff, plus customize what they gave me. Here's how the function would work:
"What's this btop1 variable on this close.htm page?" Right-click and choose "Show Definition", or Alt-Click it, or press Ctrl-F6 and it opens index.htm in the same directory and positions my cursor on the JavaScript line that says "var btop1 = new Array(5); //Stack"
or
"What does this call to link5(aNote) do?" Right-click and choose "Show Definition", or Alt-Click it, or press Ctrl-F6 and it opens functiondefs.js in the same directory and positions my cursor on the JavaScript line that says "function link5(noteString) {"
In the first case, the program looked for "var " + the string my cursor was on when I started the utility. You could even instruct the utility in preferences to search all subdirectories when the utility is invoked. In the latter case, the program looked for "function " + the string my cursor was on when I started the utility. It would search the same directory tree.