JSFiddle - React, Tailwind, and code Playground
HTML
Box - <span class="storeCheck"><input type="checkbox" /></span><br />
<input type="button" id="test" value="Click Me" />
JavaScript
$('#test').click(function() {
if($('span.storeCheck input:checked').length == 0) {
alert("Upload is only possible if a store has been chosen from list.");
}
});