JSFiddle - React, Tailwind, and code Playground

HTML

<a onclick="testif(event)" class="link" href="www.google.com">This Link is defined</a>
<a onclick="testif(event)" class="link">This Link is undefined</a>
<a onclick="testif(event)" id="cookie-page-id" href="">Hello</a>

JavaScript

function testif (e) {
  // prevent from actually going to another url
	e.preventDefault();
  var target = e.target || e.srcElement;
  if (!target.getAttribute('href')) alert("Site isn't available");
  
  var cookiepageurl = document.getElementById("cookie-page-id").href;
  if (!cookiepageurl) {
    document.getElementById("cookiesite-link").href = cookiepageurl;
    alert("hello")
  }
}