While Google attempts to render every URL Googlebot crawled, rendering may fail for various reasons. This means that if you set a JavaScript redirect, Google might never see it if rendering of the ...

This guide explains exactly how you can test whether the JavaScript on your website renders properly. Plus: 7 tools for testing and debugging JavaScript.

Once you test a URL, you can view the rendered HTML, page loading issues and a JavaScript console containing warnings and errors. And remember, this is the desktop render, not mobile.