<div class="item">
<input type="number" step="1" min="1" value="1">
<input type="chekbox">
</div>
<div class="cart"></div>
$(document).on('change', '[type="number]', function () {
var item = $(this),
container = item.closest('.item'),
otherItems = $('input', container),
theFuckingCheckboxInput = otherItems.filter('[type="chekbox"]');
console.log(item.attr('min'));
console.log(item.val());
console.log(theFuckingCheckboxInput.is(':checked'));
});