jQuery .sortable is not a function

Question

Even though I\'ve followed the directions in the jQuery UI documentation, I\'m getting the error that .sortable is not a function.
Here is my code:

Answer 1

I had the same issue when a page using the sortable() function was required by a main php page. Adding the following code within the head of the main page wasn't sufficient. Adding it also at the beginning of the required page (inside the body in my case) fixed everything.