jQuery UI slider - Cannot call method 'addClass' of undefined

I solved this error by using integers in "min", "max" and "values". Maybe you are setting null values.

The jQuery Slider specification says:

• max Number Default:100
• min Number Default:0
• value Number Default: 0

So "values" are an array of numbers.

For anyone reading back on this question, if you're pulling from a CDN, try pulling from the latest jQuery UI version. I also got this problem, and it was solved by using a later jQuery UI version.