Web Inspector and Firefox Dollar Functions

By  on  

Dollar Functions

Many of you probably didn't know this but WebKit-based like Safari and Chrome, in addition to Firefox, contain special dollar functions within the console object that allow you to grab elements within the current page.  While I've not determined the use of each method, a few of them are obvious:

// Dollar method
// Returns an element by ID
$ = function (id) {
	return document.getElementById.apply(document, arguments);
}

// Bling-Bling method
// Returns array of nodes found by QSA
$$ = function(selector) {
	return document.querySelectorAll.apply(document, arguments);
}

// Broke method
// returns the currently selected element within the console HTML pane
$0 = function toString() { [native code] }

The $1 - $4 methods are returning undefined, oddly enough.

Dollar Functions

It's not clear to me what the last few methods do.  Maybe they're placeholders for feature methods but they continue to be undefined for now.

Recent Features

  • By
    I’m an Impostor

    This is the hardest thing I've ever had to write, much less admit to myself.  I've written resignation letters from jobs I've loved, I've ended relationships, I've failed at a host of tasks, and let myself down in my life.  All of those feelings were very...

  • By
    9 Mind-Blowing WebGL Demos

    As much as developers now loathe Flash, we're still playing a bit of catch up to natively duplicate the animation capabilities that Adobe's old technology provided us.  Of course we have canvas, an awesome technology, one which I highlighted 9 mind-blowing demos.  Another technology available...

Incredible Demos

  • By
    Dynamically Load Stylesheets Using MooTools 1.2

    Theming has become a big part of the Web 2.0 revolution. Luckily, so too has a higher regard for semantics and CSS standards. If you build your pages using good XHTML code, changing a CSS file can make your website look completely different.

  • By
    MooTools, Mario, and Portal

    I'm a big fan of video games. I don't get much time to play them but I'll put down the MacBook Pro long enough to get a few games in. One of my favorites is Portal. For those who don't know, what's...

Discussion

  1. Brian

    $0 returns whatever you have selected in the Elements tab.

    These all work in Firebug too, by the way.

  2. $0 and $1 return the currently selected DOM element and the previously selected DOM element, respectively. I haven’t yet found a use for this while debugging, mainly because selecting elements in the inspector and debugging in the console seem (for me at least) to be disconnected tasks, but maybe there will be a reason some day? ^_^

    Not sure about webkit’s inspector, but you can find the API for firebug’s CLI here: http://getfirebug.com/wiki/index.php/Command_Line_API

  3. Matthew F

    Perhaps if they plan to use it in the future, they have to reserve it now so that the dom-modifying frameworks don’t start using it :)

  4. Didn’t know about this, the bling-bling method is cool though, haha.

  5. farkob

    Now I get it, this is why Douglas Crockford says you shouldn’t use $ functions.

Wrap your code in <pre class="{language}"></pre> tags, link to a GitHub gist, JSFiddle fiddle, or CodePen pen to embed!