validate both dropdown and listview checkboxes+Javascript

I have checkboxes in one column of  listview and outside the listview I have one  dropdown and
one button.
when I dont check any checkboxes in listview  fire a validation "Select any one checkbox" on button click.
simirarly when I check Checkboxes in listview and I'm leaving to select dropdown fire a validation"Select any item in the dropdownlist" on button click.


how to validate both controls(checkboxes in listview and dropdown) when those are not selecting.

Many thanks in advance.








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