Gary Illyes from Google said on Twitter it is probably not a good idea to use JavaScript redirects. This was specific to redirecting users based on their location to a country specific version of the page. But Google has said before that server side redirects are the best.
Here is Gary's tweet:
Js redirects are probably not a good idea though.
— Gary 鯨理／경리 Illyes (@methode) July 8, 2020
In 2016, John Mueller said on Google+ (trust me, there was a Google+) "JavaScript redirects: If you can’t do a server-side redirect, using JavaScript is a good fall-back. If you’re using a JavaScript framework for your site, this might also be the only option. Caching depends on the server settings, and search engines have to guess at what you’re trying to do (index under R or S?)."
In 2010, John also told people to shy away from using meta refresh-type or JavaScript redirects.
Go server side when it comes to implementing redirects.
Forum discussion at Twitter.
