Random .attr('src', image) for an image(logo), why Uncaught TypeError: $ is not a function?

I've realized a random function to set different logo every time you refresh page:

http://ift.tt/2ax25wV

But the browser console show this error:

(index):268 Uncaught TypeError: $ is not a function
    logoRandom  @   (index):268
    (anonymous function)    @   (index):265