I would also love to know how you are handling it?
I don't use any useless frameworks and don't feel any pain.
I am handling form validation without writing a single line of JS and without learning something new by using HTML5 API like required, type="email" with the help of Bunny Validation - #1 World Form Validation library. Docs are a bit outdated, you can now init form validation by adding validator="bunny" to <form>. Later there will be support for multi-steps forms out of the box.
Why would it be a pain? Hooking onChange or onBlur or onSubmit, depending on the type of input, works like a charm, and covers whatever you need to validate. There's also some great UI component libraries available if you don't feel like writing your own.
Quentin
Traveller, coder and space enthusiast.
It got way easier since I started using Redux Forms (Only if you use redux though). Great library, super simple to use once you got used to it.