How to group DIVs to one DIV using jQuery?

I have several DIVs with same class, and I need using jQuery or pure JS group it into one DIV

<div class="a">
    <div>1</div>
</div>
<div class="a">
    <div>2</div>
</div>
<div class="a">
    <div>3</div>
</div>

and I need it looks like:

<div class="new-class">
  <div class="a">
    <div>1</div>
  </div>
  <div class="a">
    <div>2</div>
  </div>
  <div class="a">
    <div>3</div>
  </div>
</div>

I can’t change HTML, only can use JS

>Solution :

use wrapAll method

$(".a").wrapAll("<div class='new-class'></div>")

.new-class {
  color: red;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div class="a">
    <div>1</div>
</div>
<div class="a">
    <div>2</div>
</div>
<div class="a">
    <div>3</div>
</div>