Rerference error: $j is not defined in optcheckout_rwd.js - Checkout as guest button not working - Magento 1.9

Question

I'm getting a strange error on my Magento 1.9.0.1 website.

We have recent modified the RWD theme quite heavily, aesthetically.

When we progress to step 1 of the checkout process, the continue button beneath the:

"Checkout as a Guest or Register"

Throws this JS error up and doesn't work, however, if you input a username and password (registered customer) the login button works fine...

" ReferenceError: $j is not defined opcheckout_rwd.js:29 "

Its in relation to this line of code in the JS file (line 29):

" $j('body').addClass('opc-has-progressed-from-login'); "

I have tried to comment out the line, this works but then the checkout behaves quite strange and doesn't display the accordion titles or the summary of your progression on the right hand side.

Any advice would be greatly appreciated.

Answer 1

Check that Jquery is being loaded into the page. If not add it to your local.xml file or similar