JSFiddle - React, Tailwind, and code Playground
HTML
<div class="checkbox-group required" id="uno">
<input type="checkbox" name="checkbox_name[]" >
<input type="checkbox" name="checkbox_name[]">
<input type="checkbox" name="checkbox_name[]">
<input type="checkbox" name="checkbox_name[]">
</div>
<div class="checkbox-group required" id="due">
<input type="checkbox" name="checkbox_name2[]" >
<input type="checkbox" name="checkbox_name2[]">
<input type="checkbox" name="checkbox_name2[]">
<input type="checkbox" name="checkbox_name2[]">
</div>
<div class="checkbox-group required" id="tre">
<input type="checkbox" name="checkbox_name3[]" >
<input type="checkbox" name="checkbox_name3[]" >
<input type="checkbox" name="checkbox_name3[]">
<input type="checkbox" name="checkbox_name3[]">
</div>
<input type="button" value="test" onclick="prova()" />
JavaScript
function prova()
{
alert(
'primo gruppo: ' + (document.querySelectorAll('div.checkbox-group.required#uno input:checked').length > 0)
);
alert(
'secondo gruppo ' + (document.querySelectorAll('div.checkbox-group.required#due input:checked').length > 0)
);
alert(
'terzo gruppo ' + (document.querySelectorAll('div.checkbox-group.required#tre input:checked').length > 0)
);
}