How do you get id from the previous and the next div through js?

[Alberto]

How do you get id from the previous and the next div through js? And if it's over, it's done. alert('Закончилось!');

/* PREV */
$(".prev").on("click", function() {
  $("div.active:not(:first-child)").removeClass("active").prev().addClass("active").click();
});
/* NEXT */
$(".next").on("click", function() {
  $("div.active:not(:last-child)").removeClass("active").next().addClass("active").click();
});

body {
  background: #EEE;
}
div {
  width: 100px;
  height: 150px;
  background: #FFF;
  color: #555;
  margin: 10px;
  float: left;
}
div.active {
  background: #555;
  color: #FFF;
}
button {
  float: left;
  font-size: 12px;
  margin: 5px;
  padding: 8px 8px;
  color: #FFF;
  background: #555;
  cursor: pointer;
  border: 0;
}
button:hover {
  background: #444;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="1">
  Block 1
</div>
<div id="2" class="active">
  Block 2
</div>
<div id="3">
  Block 3
</div>
<button class="prev">
  Предыдущий id 1
</button>
<button class="next">
  Следующий id 3
</button>

[rosemadder]

Turn the div's into the general container and rewrite the selters for the .prev() and .next()to look inside this container. Then for the first element. https://api.jquery.com/prev/ return the empty jQuery target. Same for the last one. .next()♪

But it's better to know all the id elements in advance, jump, keep them in the mass. Maintain the variable meaning of the current, and press the buttons forward/to change the meaning of this variable, if possible. And rewrite the styles by running through everything, or by changing the former current and new.