JSFiddle - React, Tailwind, and code Playground

HTML

<h3>foo<span>bar</span><div>baz</div>bam</h3>
<br/>
<h3>foo<span>bar</span><div>baz</div>bam</h3>

JavaScript

$("h3:first").wrapInner(function(i) {
    console.log(this);
    return "<strong style='display:block;border:1px solid #000'/>";
});
$("h3:eq(1)").wrapInner("<strong style='display:block;border:1px solid #000'/>");