JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="//code.jquery.com/ui/1.11.4/themes/smoothness/jquery-ui.css">
<script src="//code.jquery.com/jquery-1.10.2.js"></script>
<script src="//code.jquery.com/ui/1.11.4/jquery-ui.js"></script>
<link rel="stylesheet" href="jqueryui.com/resources/demos/style.css">
<div id="format">
    <input type="checkbox" id="check1"/><label for="check1">Alpha</label>
    <input type="checkbox" id="check2"/><label for="check2">Bravo</label>
    <input type="checkbox" id="check3"/><label for="check3">Charlie</label>
</div>

CSS

#format{
    -webkit-touch-callout: none;
    -webkit-user-select: none;
    -khtml-user-select: none;
    -moz-user-select: none;
    -ms-user-select: none;
    user-select: none;
}

JavaScript

var shiftDown = false;

$( "#format" ).buttonset();

$(document).on('keydown', function(e){
    if(e.which == 16 && !shiftDown){ shiftDown = true; }
});
$(document).on('keyup', function(e){
    if(e.which == 16 && shiftDown){ shiftDown = false; } 
});

$('#format label').on('click', function(){
    if(shiftDown){
        //$(this) was clicked while shift was down
    }
    else{
        //$(this) was clicked while shift was not down   
    }
});