jQuery not working on code pen?

I’ve added the library and made a function to change the body background to black when the web page has loaded but have gotten nothing. Here’s the code pen:http://codepen.io/david_vu408/pen/MJJrBv. Can anyone see the mistake?

1 Like

Hey there! You have to put “body” in quotations.

By the way, try using your dev console. It’s an excellent tool for debugging. It was showing that “body” wasn’t defined.

Have you tried with both jQuery and jQuery UI? I had problems at first with it too, but jQuery UI fixed my problems.



if you have mixed http/https libs, codepen will not allow it to run unless the libs are over https


open your BROWSER dev console when running your code, don’t rely on codepen console to catch a LOT of stuff.

This is CodePen console from YOUR pen:

"jQuery.Deferred exception: body is not defined" "@pen.js:26:5
" undefined

This is my MSedge console from your pen"

An iframe which has both allow-scripts and allow-same-origin for its sandbox attribute can remove its sandboxing.  MJJrBv
updateBlockedAdsCount 1  frames.js:329
jQuery.Deferred exception: body is not defined @pen.js:26:5
 undefined  console_runner-5710c30fb566082d9fcb6e7d97ee7e3f2a326128c9f334a4231b6fd752b29965.js:1:2206
ReferenceError: body is not defined[Learn More]  index.html:26:5
	<anonymous> pen.js
	g/</j https://cdnjs.cloudflare.com/ajax/libs/jquery/3.1.0/jquery.min.js:2:29566
	g/</k< https://cdnjs.cloudflare.com/ajax/libs/jquery/3.1.0/jquery.min.js:2:29882

So all you need is for the background to transition from blue to black when it loads, right? Because in JS I see you have background color being blue.

By the way, the reason why it’s giving you ReferenceError: body is not defined is because instead of

you should do this

body must be in quotation marks, otherwise your function won’t work.
It’s in one of the jQuery lessons .


Ahhhh! Just a quick fix, quotation marks around body. Thank you everyone!

1 Like