Is create React App bad for SEO?

Right out of the box, a standard HTML and CSS website, not using React.js, is generally a much better SEO option. However, if React.js has server-side rendering, this makes it much more viable as an SEO option. Having a fast-loading website, that is also responsive on tablets and phones, is very important, however, the initial goal must be to make it easy for search engines to crawl the website information effectively. Most search engines initially crawl the HTML and CSS and then index the website and pages. However, when React.js is present, the vast majority of content is generated by Javascript.

Because of this, when a crawler first views the website code it sees an empty div tag with no code showing within the div tag. Google is the only current search engine that can crawl Javascript effectively and this is because it is expensive for search engines to complete this aspect. Bing, Yahoo, and other search engines will basically ignore React.js pages, so the traffic on these search engines will most likely go to competitors. Google crawlers are much more advanced than other search engines. Google crawlers do have the ability to crawl and render JavaScript and will index the website.

Another downside of using React App is that Google will crawl the site much less often and this can have a negative effect, as new content won't be crawled as often as a standard HTML and CSS website. Overall, React.js is not recommended for SEO in current times.

@kaylin 

In summary, using Create React App without server-side rendering can have some negative effects on SEO. Other search engines, such as Bing and Yahoo, may not be able to crawl and index the content effectively, causing potential loss of traffic from these sources. Additionally, Google crawlers may crawl the site less frequently, resulting in slower indexing of new content.