Why am I able to use jQuery syntax in Chrome's JS console when current page doesn't have jQuery loaded?

Question

I thought one has to have jQuery source loaded first in order to use $ to target elements. I was on a webpage that doesn't even include any scripts but somehow I was able to run $('body') inside the Javascript console and Chrome successfully returned its value.

Why didn't I get a syntax error like 'undefined token'? Thanks.

I'm not able to reproduce this on http://www.this-page-intentionally-left-blank.org/ — Shmiddty, Nov 15 '12 at 17:20
Tried with all plugins/extensions disabled and got same result. — , Nov 15 '12 at 17:27
Duplicate: [$ variable-in-chrome](http://stackoverflow.com/questions/11778477/variable-in-chrome) — jfrej, Nov 15 '12 at 17:36
Thanks @jfrej that makes sense. I tried `jQuery('body')` and got 'jQuery not defined' so it's pretty clear now. — , Nov 15 '12 at 17:45

Florian Margaine · Accepted Answer · 2012-11-15T17:59:23.880

10

Before, Chrome had an alias to document.getElementById with the $ variable.

Recently (probably on Chrome 23 release), it has been changed to an alias to document.querySelector.

So your code is the equivalent of document.querySelector('body').

edited Nov 15 '12 at 17:59

answered Nov 15 '12 at 17:52

Florian Margaine

58,730
15
91
116

score 0 · Answer 2 · answered Nov 15 '12 at 17:36

0

As already alluded to in the comments by @Shmiddty, it is likely due to a plugin you have installed...

You can find out by running developer tools, select 'Sources' and look at both the Sources and Content Scripts panes - is something suspiciously like jQuery in there somewhere?

answered Nov 15 '12 at 17:36

babelmonk

134
6

1

Nope, it's a Dev Tools function: http://stackoverflow.com/questions/11778477/variable-in-chrome – jfrej Nov 15 '12 at 17:38
@jfrej The Dev Tools is only an alias to `getElementById`, using `$('body')` wouldn't work unless there is an element with the id `body`. – Florian Margaine Nov 15 '12 at 17:40
My bad. It seems like it also loads `body`. Weird. – Florian Margaine Nov 15 '12 at 17:41
Oh, interesting! Thanks for the clarification! – babelmonk Nov 15 '12 at 17:42
@jfrej FWIW, this has recently been changed. Probably Chrome 23. – Florian Margaine Nov 15 '12 at 17:56

Why am I able to use jQuery syntax in Chrome's JS console when current page doesn't have jQuery loaded?

2 Answers2

Linked