I also think that location.replace(URL) is the best way, but if you want to notify the search engines about your redirection (they don't analyze JavaScript code to see the redirection) you should add the rel="canonical" meta tag to your website.
Adding a noscript section with a HTML refresh meta tag in it, is also a good solution. I suggest you to use this JavaScript redirection tool to create redirections. It also has Internet Explorer support to pass the HTTP referrer.
Sample code without delay looks like this:
<!-- Place this snippet right after opening the head tag to make it work properly -->
<!-- This code is licensed under GNU GPL v3 -->
<!-- You are allowed to freely copy, distribute and use this code, but removing author credit is strictly prohibited -->
<!-- Generated by http://insider.zone/tools/client-side-url-redirect-generator/ -->
<!-- REDIRECTING STARTS -->
<link rel="canonical" href="https://yourdomain.example/"/>
<noscript>
<meta http-equiv="refresh" content="0;URL=https://yourdomain.example/">
</noscript>
<!--[if lt IE 9]><script type="text/javascript">var IE_fix=true;</script><![endif]-->
<script type="text/javascript">
var url = "https://yourdomain.example/";
if(typeof IE_fix != "undefined") // IE8 and lower fix to pass the http referer
{
document.write("redirecting..."); // Don't remove this line or appendChild() will fail because it is called before document.onload to make the redirect as fast as possible. Nobody will see this text, it is only a tech fix.
var referLink = document.createElement("a");
referLink.href = url;
document.body.appendChild(referLink);
referLink.click();
}
else { window.location.replace(url); } // All other browsers
</script>
<!-- Credit goes to http://insider.zone/ -->
<!-- REDIRECTING ENDS -->
