<div class="black active"></div>
<div class="white"></div>
<button class="add-to-bag"></div>
var selectors = ['black', 'white'];
$(".add-to-bag").click(function() {
var $this = $(this);
$.each(selectors, function(index, value ) {
if($('.'+value).hasClass("active")) {
console.log(value);
$this.attr("href", value+".html")
}
});
});