JSFiddle - React, Tailwind, and code Playground

HTML

<div class="message">
    <span>Menu 1</span><span>Menu 2</span>
</div>

CSS

.message span {
 border: 1px solid red;   
 display: inline;
 margin: 0;
 padding: 0;
}

JavaScript

var content = $('.message').html();
content = content.substring(5, content.length-1);
console.log("|"+content+"|")
content = content + "<span>Menu 3</span>"
console.log("|"+content+"|")
$('.message').html(content);