JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div class="post-body">
<a href="http://subdomain.blogspot.com/jsjeieksmamssmssnsbbsbs">1 الرابط</a><br/>
<a href="http://subdomain.blogspot.com/jsjeieksmamssmssnsbbsbs">الرابط 2</a><br/>
<a href="http://subdomain.blogspot.com/jsjeieksmamssmssnsbbsbs">الرابط 3</a><br/>
<a href="http://subdomain.blogspot.com/jsjeieksmamssmssnsbbsbs">الرابط 4</a><br/>
<a href="http://subdomain.blogspot.com/jsjeieksmamssmssnsbbsbs">الرابط 5</a><br/>
</div>

JavaScript

$(document).ready(function() {

 var sub = new Array("subdomain2", "subdomain3", "subdomain4", "subdomain");
     var randno = Math.floor(Math.random()*(sub.length));
    
    $(".post-body a" ).each(function() {
    var old = $(this).attr('href').replace('subdomain', randno);
     $(this).attr('href', old);
     });
});