Deferred JavaScript Rendering

When it first launched, the process of deferring, rendering, crawling and indexing JavaScript could delay the indexing of content in JavaScript for up to a week. Now, as the system has evolved, it is estimated to take up to a few days, or less. This delay can impact Google’s understanding of the site, if they get radically different content in the first and second pass of the website. It is for this reason that Google and most SEOs recommend that websites with important content in navigation used a process called server-side rendering or a similar but different process called universal or isomorphic JavaScript rendering to ensure that JavaScript code is executed and turned into a flat HTML file at the server, before it is sent to the browser.