Knockout 2.2.0 error with jQuery 1.9

Question

I copied one of examples of knockoutjs:

Answer 1

Updating Knockout to 2.2.1 solves the problem for me:

• 2.2.0: http://jsfiddle.net/UDSBC/2/
• 2.2.1: http://jsfiddle.net/UDSBC/1/

So just change:

<script src="http://cdnjs.cloudflare.com/ajax/libs/knockout/2.2.0/knockout-min.js"></script>

To:

<script src="http://cdnjs.cloudflare.com/ajax/libs/knockout/2.2.1/knockout-min.js"></script>

And it'll work.

Answer 2

The Cause

You are not using the most current version of Knockout. The previous version, 2.2.0, is incompatible with jQuery 1.9.x and on. See this Knockout dev thread:

Knockout 2.2.0 uses jQuery.clean() which is deprecated and does not exist in 1.9.

This means that Knockout 2.2.0 is calling an undefined jQuery method, thus triggering the JS error you specified.

Solutions

1. Consider updating to the latest version of Knockout which is compatible with jQuery 1.9
2. If you can't, use the jQuery Migrate plugin which adds backward-compatibility to jQuery 1.9
3. If all else fails, you'll need to revert back to jQuery 1.8