JavaScript and SEO, all you wanted to know.Pre-loading the DOM first is advisable.
On your website - be crawlable for both Googlebot and Caffeine alike.
Google and Caffeine are often mixed-up even by Google's staff members.
Make sure your content does not depend solely on JavaScript, but also on HTML.
In the future Googlebot may render newest JavaScript.
(now renders 2018 script through the 69 version of the browser,
later will come to use the latest version);
writing isomorphic Javascript being pre-rendered on the webserver may help SEO,
and load performance, but the apt developer must have the capacity to implement this.
Google plans to integrate crawling and rendering, as planned at their 2018 Chrome Dev Summit,
but JavaScript issues may remain, so there will still will be reports coming from analysts like little old me.
Info credits go to Marketingfacts JavaScript & SEO,
all you should know by Tom Wester SEO-strategist at RIFF's.Test your performance on the client and webserver here,->
https://gtmetrix.com/reports/Enjoy, my good avast friends, enjoy,
polonus (volunteer 3rd party cold reconnaissance website security analyst and website error-hunter)