JSFiddle - React, Tailwind, and code Playground

HTML

<input type="checkbox" id="radio1" name="radio" value="1" /><label for="radio1">Choice 1</label>
<input type="checkbox" id="radio2" name="radio" value="2"  /><label for="radio2">Choice 2</label>
<input type="checkbox" id="radio3" name="radio" value="3" /><label for="radio3">Choice 3</label>

JavaScript

function check_checked() {
    var notChecked = $('input:not(:checked)')
    var outputText = 'These checkboxes are not checked: ';
    for (i=0; i<notChecked.length; i++) {
        outputText += notChecked[i].value +', '; 
    }
    alert(outputText.slice(0, -2));
}    

$('input').on('click', function() {
    check_checked();   
});