Component Migration to Version 4

[jschmi102]

hi,
I'm on my way to migrate a component from V3 to V4. And I had some problems for which I sofar did not find a solution - mainly because there is no documentation at all for these tasks. For examle I got stuck now with this:
V3 had a couple of very helpful utility classes in behaviour.php - e.g. you could use formvalidation using "HTMLHelper::_('behavior.formvalidation');" - all this is gone, - where? I could not find out. Is there any doc for developers to find a replacement or solution for replaced or changed APIs? The only thing I found out sofar is that functions are gone - no doc for a replacement or a solution. This is really frustrating.

[brianteeman]

I would start out here https://docs.joomla.org/JDOC:Joomla_4_Tutorials_Project and pay specific attention to https://docs.joomla.org/Joomla_4_Tips_and_Tricks:_Form_Validation_Basics