First: I searched a lot and I can't find anyone to have this problem (it seems like it something basic, but I have been 2 hours dealing with this).
My problem is that long ago I had the javascript validator for eclipse. I don't know why I don't have it anymore, but I want it back.
I found this and tried to do the inverse: How do I remove javascript validation from my eclipse project?
But my problem is that when I click Properties under my project, I can't find the "Javascript" tab.. Why? I think the problem is here, I tried modifying anything else under validators, also under window->Preferences->Javascript or Validtors->Client-side Javascript..
Also I don't have the JavaScript Validator under Builders.
EDIT:
This is what I see on my project properties:
This is what I see under validation
This is what I see under Builders