Sync client-side and server-side validation

[jonybekov]

Hi guys!

In our current project, we want to validate our rich text editor value on both, front-end and back-end.
As a rich text editor, we use UUI component which uses slate.js under the hood.
On front, we can set max character count and it's easy to validate text content.
On backend, we can't rely on any reasonable number, because the size of generated JSON by Slate is highly depends on the number of formattings.

Any ideas of how we can sync validation between front and backend?