<div id="black" class="item">1</div>
<div id="white" class="item item__active">2</a>
<div id="yellow" class="item">3</a>
<div id="gray" class="item">4</a>
<a class="btn">клик</a>$(".item").click(function() {
$(".btn").attr("href", $(this).attr("id") + ".html")
})
External CSS
This Pen doesn't use any external CSS resources.