JSEnv live XPath visualizer

I've had some productive hack weekends recently -- last weekend, among other things, I took a plunge into the Firebug 1.1 beta, both to re-apply a rather useful feature patch I submitted upstreams a year ago (which was lost, and found, and lost and found again -- might make 1.2) and to add some handy keyboard shortcuts to the HTML view (deleting nodes with delete and backspace, and both folding/unfolding and stepping up/down the DOM tree with arrow left and right).

Anyway, I ended up excavating Firebug's highlight-a-node code to turn it into a tiny lib and then use that lib for beefing up Jesse Ruderman's jsenv bookmarklet with a live edit XPath field highlighting all matches in the page as you type:

screenshot of the live XPath visualizer

It tells you what the expression matches in the title bar of the jsenv window, and signals some additional colour coded info via the XPath input field's border:

  • red for illegal expressions,
  • green for matching nodes,
  • gray for 0 matched nodes,
  • yellow for a string,
  • blue for a number and
  • magenta for a boolean value.
Ah, one more feature -- you move the focus node you see with arrow up and down in the input field, or scroll wheel up/down when hovering it.

The ideal spot for this feature would probably be as an extra feature to toggle on and off in Firebug's HTML view -- to filter the view by, for instance. The more I think of it, the more useful this feature would be in that shape. I hope the Firebug Working Group is as open to additional community developers as it seems to aim for.

Anyway, here is the XPath jsenv; enjoy!
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