JSFiddle - React, Tailwind, and code Playground

HTML

<input type="button" onclick="get_content()" value="Get Content"/>
<p id='txt'>
<span class="A">I am </span>
<span class="B">working in </span>
<span class="C">ABC company.</span>
</p>

JavaScript

function get_content(){
   var p = document.getElementById("txt");
   var spans = p.getElementsByTagName("span");
   var text = '';
   for (var i = 0; i < spans.length; i++){
       text += spans[i].innerHTML;
   }
    
   p.innerHTML = text;
}