[forms] Using the HTML5 "required" attribute for a group of checkboxes?

I added an invisible radio to a group of checkboxes. When at least one option is checked, the radio is also set to check. When all options are canceled, the radio is also set to cancel. Therefore, the form uses the radio prompt "Please check at least one option"

  • You can't use display: none because radio can't be focused.
  • I make the radio size equal to the entire checkboxes size, so it's more obvious when prompted.

HTML

<form>
  <div class="checkboxs-wrapper">
    <input id="radio-for-checkboxes" type="radio" name="radio-for-required-checkboxes" required/>
    <input type="checkbox" name="option[]" value="option1"/>
    <input type="checkbox" name="option[]" value="option2"/>
    <input type="checkbox" name="option[]" value="option3"/>
  </div>
  <input type="submit" value="submit"/>
</form>

Javascript

var inputs = document.querySelectorAll('[name="option[]"]')
var radioForCheckboxes = document.getElementById('radio-for-checkboxes')
function checkCheckboxes () {
    var isAtLeastOneServiceSelected = false;
    for(var i = inputs.length-1; i >= 0; --i) {
        if (inputs[i].checked) isAtLeastOneCheckboxSelected = true;
    }
    radioForCheckboxes.checked = isAtLeastOneCheckboxSelected
}
for(var i = inputs.length-1; i >= 0; --i) {
    inputs[i].addEventListener('change', checkCheckboxes)
}

CSS

.checkboxs-wrapper {
  position: relative;
}
.checkboxs-wrapper input[name="radio-for-required-checkboxes"] {
    position: absolute;
    margin: 0;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    -webkit-appearance: none;
    pointer-events: none;
    border: none;
    background: none;
}

https://jsfiddle.net/codus/q6ngpjyc/9/

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