2. Scroll down and find the "Rocket Loader"
If you see various types of errors or faced with some other problems while working with Frontend or Backend Editor in KingComposer, most likely the issues caused by “Cloudflare”.
So, if you got issues with JavaScript or jQuery or other errors, please do the following:
Turn off the “Rocket Loader” in your Performance Settings. You can get to your Performance Settings by going to Speed > Rocket loader of your personal account:
1. Select "Speed" tab
2. Scroll down and find the "Rocket Loader"
3.Switch on "Off"
Otherwise, you can get to your performance settings by replacing the domain in the following URL:
https://www.cloudflare.com/cloudflare-settings?z=YOURDOMAIN.COM#page=performance
Official documentation: