How to validate textarea and checkboxes which are generated dynamically

This one seems really common question in StackOverflow. However, I am having difficulty in validating these textarea (Not to left blank) and checkboxes(At least one should be checked). I tried several validation Javascripts and frameworks but in vain.

I have textarea named "case_title0[]" whose will increase the number "0" to "1","2" and so on when user clicks "Add More" button. I want to validate at the point when user clicks the "Add More" button.

Secondly, I want the checkbox (name="editioncheck'+caseNum+'[]") which is dynamic as well to restrict user to leave it blank. The checkbox looks like "editioncheck0[]", "editioncheck1[]" and so on. It needs to be checked at least once to proceed to next "Add More" button. Until then "Add More" button should remain inactive.

So, I want these two type of validation in my form ie. textarea and checkbox.

Which is the simplest framework or custom code to use here?

I don't want fancy display as just alert() box should work in this regard.