Follow Google’s progressive enhancement principles; start here:
- Content must be accessible to all browsers, as should their basic functionality
- Use semantic markup, which wraps all content
- Link your CSS & JS externally; these assets are what improves your layout & enhancing behavior
Progressive enhancement effectively deprecated Google’s AJAX Crawling Specification in October 2015 (it was introduced early 2009); more about that here. What this means: Google has adopted a more progressive approach towards crawling a web page/web app. This is great news, granted you follow Google’s basic SEO principles! If you don’t, it won’t be very hard to wrap your head around it with a plethora of SEO best practices available at Google (Webmaster Principles) and right here in our search engine optimization blog.
Follow Google’s Webmaster Principles:
- Make pages for users (not robots)!
- Don’t deceive users
- Avoid tricks to improve rank (like auto generated content, hidden text, doorway pages, sneaky redirects, scraped content, etc)
- Think about what makes your website unique, valuable, or engaging. Make your website stand out from others in your field.
In short: make websites & apps for users, follow the basic principles of progressive enhancement, along with Google webmaster guidelines, and you’ll do well!
Source: Core Principles of SEO for JS