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
    6 Things You Didn’t Know About Firefox OS

    Firefox OS is all over the tech news and for good reason:  Mozilla's finally given web developers the platform that they need to create apps the way they've been creating them for years -- with CSS, HTML, and JavaScript.  Firefox OS has been rapidly improving...

  • By
    7 Essential JavaScript Functions

    I remember the early days of JavaScript where you needed a simple function for just about everything because the browser vendors implemented features differently, and not just edge features, basic features, like addEventListener and attachEvent.  Times have changed but there are still a few functions each developer should...

Incredible Demos

  • By
    Comment Preview Using MooTools

    Comment previewing is an awesome addition to any blog. I've seen really simple comment previewing and some really complex comment previewing. The following is a tutorial on creating very basic comment previewing using MooTools. The XHTML You can set up your XHTML any way you'd like.

  • By
    Font Replacement Using Cufón

    We all know about the big font replacement methods. sIFR's big. Image font replacement has gained some steam. Not too many people know about a great project named Cufón though. Cufón uses a unique blend of a proprietary font generator tool...

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!