How can I do that via Corvid-Coding, to say that for example the RichtText-Box valiation failed and now please show it to the user. I can only use JavaScript.
How can I do that?
And how work those two function?
The Corvid: About Validating User Input with Code will give you a good start.
Thanks for it.
But I created my own validation-system 
Also the live editor example too.
https://www.wix.com/corvid/example/custom-validations