Introduction to JavaScript and SEO
Google’s Martin Splitt recently shared insights on how JavaScript mistakes can hurt a website’s search performance. His talk comes as Google Search Advocate John Mueller also urges SEO pros to learn more about modern client-side technologies. This article will explore the common mistakes made when using JavaScript and how to debug them.
Common JavaScript Mistakes
There are several common mistakes made when using JavaScript that can negatively impact a website’s search performance. These mistakes include:
Rendered HTML vs. Source HTML
Many SEO professionals still focus on the website’s original source code, even though Google uses the rendered HTML for indexing. Rendered HTML is what you see after JavaScript has finished running. Splitt explains, "A lot of people are still looking at view source. That is not what we use for indexing. We use the rendered HTML." This is important because JavaScript can change pages by removing or adding content, which can help explain some SEO issues.
Error Pages Being Indexed
Splitt pointed out a common error with single-page applications and JavaScript-heavy sites: they often return a 200 OK status for error pages. This happens because the server sends a 200 response before the JavaScript checks if the page exists. Splitt explains, "Instead of responding with 404, it just responds with 200 … always showing a page based on the JavaScript execution." When error pages get a 200 code, Google indexes them like normal pages, hurting your SEO.
Geolocation Request Issue
Another problem arises when sites ask users for location or other permissions. Splitt says Googlebot will always refuse the request if a site relies on geolocation (or similar requests) without a backup plan. Splitt explains, "Googlebot does not say yes on that popup. It says no on all these requests … so if you request geolocation, Googlebot says no." The page can appear blank to Googlebot without alternative content, meaning nothing is indexed, which can turn into a grave SEO mistake.
Debugging JavaScript for SEO
To debug JavaScript issues, Splitt shared a few steps:
- Start with Search Console: Use the URL Inspection tool to view the rendered HTML.
- Check the Content: Verify if the expected content is there.
- Review HTTP Codes: Look at the status codes in the "More info" > "Resources" section.
- Use Developer Tools: Open your browser’s developer tools. Check the "initiator" column in the Network tab to see which JavaScript added specific content.
A Shift in SEO Skills
Splitt’s advice fits with Mueller’s call for SEOs to broaden their skill set. Mueller recently suggested that SEO professionals learn about client-side frameworks, responsive design, and AI tools. Mueller stated, "If you work in SEO, consider where your work currently fits in … if your focus was ‘SEO at server level,’ consider that the slice has shrunken." Modern JavaScript techniques create new challenges that old SEO methods cannot solve alone.
What This Means for SEO Professionals
Both Google Advocates point to a clear trend: SEO now requires more technical skills. As companies look for professionals who can blend SEO and web development, the demand for these modern skills is growing. To keep up, SEO pros should:
- Learn How JavaScript Affects Indexing: Know the difference between source and rendered HTML.
- Master Developer Tools: Use tools like Search Console and browser developer tools to spot issues.
- Collaborate with Developers: Work together to build sites that serve users and search engines well.
- Broaden Your Skillset: Add client-side techniques to your traditional SEO toolkit.
Conclusion
In conclusion, JavaScript mistakes can hurt a website’s search performance, but by understanding the common mistakes and learning how to debug them, SEO professionals can improve their skills and stay up-to-date with the latest trends. By following the steps outlined in this article and broadening their skill set, SEO pros can ensure that their websites are optimized for both users and search engines. As the web evolves, it’s essential for SEO professionals to adapt and learn new skills to remain relevant in the industry.