Should you still optimize JavaScript for search engines other than Google?

Why does Google emphasize this distinction?

Martin Splitt clarifies the scope of his statements: he is only speaking about Google Search. This reminder is not trivial — it signifies that an optimal JavaScript architecture for Google does not guarantee anything elsewhere.

Other engines have different compute budgets, infrastructures, and priorities. Bing has long had limited JS rendering, Yandex focuses on certain regional markets, and DuckDuckGo partially relies on Bing. Each makes trade-offs between speed, crawl cost, and rendering quality.

What does this mean for a JavaScript site?

If 95% of your traffic comes from Google, the risk is low. However, as soon as you target markets where Bing or Yandex are significant (Russia, certain B2B segments in the United States), or if you are banking on diversifying your sources, relying on JS rendering becomes risky.

The issue doesn't only arise at launch. A framework change, a major update, a poorly managed new component: anything can break indexing on a secondary engine without you immediately noticing it in your Google-centric KPIs.

Does Google implicitly acknowledge a limit to its own JS rendering?

By specifying that he speaks " specifically about Google Search ", Splitt admits that JavaScript rendering is not a universal commodity. It is a costly technical capability, subject to trade-offs.

Even Google does not render everything instantly: there is a queue, a crawl budget, and priorities. Other engines make the same trade-offs, often with fewer resources. The result: what works at Google can fail elsewhere without you having changed a line of code.

• Google renders JavaScript, but this capability is not uniformly shared by Bing, Yandex, or DuckDuckGo.
• Technical compromises vary: crawl budgets, indexing priorities, and server-side rendering costs differ from one engine to another.
• A fully client-side site may be invisible on some engines even if it performs on Google.
• Diversifying traffic sources requires a multichannel-compatible rendering architecture (SSR, prerendering, hydration).
• The risk increases in non-English-speaking markets where Google is not dominant (Russia, China, certain B2B segments).

Is this statement consistent with field observations?

Absolutely. Tests conducted on Bing regularly show that JS rendering is partial, slow, or nonexistent depending on configurations. A React or Vue.js site performing well on Google may display blank pages in Bing's index, especially if the content relies on asynchronous API calls.

Yandex has traditionally favored conventional architectures. DuckDuckGo, which partially relies on Bing, inherits the same limitations. The promise of " JavaScript works everywhere " is a myth that Google itself does not endorse.

What nuances should be added to this position?

Splitt speaks of " trade-offs ". That's an understatement. In reality, some engines make no effort at JS rendering, others do it sporadically or selectively. There is no standard, no guarantee.

[To verify]: Google does not publish any comparative metrics on the rendering capabilities of other engines. We're navigating by intuition, based on empirical tests and field feedback. The absence of official data complicates any diagnosis.

In what cases does this rule not apply?

If you are in a sector where Google captures 98% of organic traffic (e-commerce for general consumers in France, for example), the risk is marginal. However, once you target B2B niches, international markets, or segments where Bing has a significant share, ignoring this reality can be costly.

Another case: content aggregators, vertical engines, and third-party crawlers (LinkedIn, Pinterest, SEO tools) generally do not render JS. If your visibility depends on these channels, a pure client-side architecture is a structural handicap.

What should you do if targeting multiple engines?

Prioritize an SSR (Server-Side Rendering) architecture or prerendering: Next.js, Nuxt.js, or prerendering solutions like Prerender.io ensure that the HTML is already built before the bot arrives. This is the only reliable defensive approach.

If you are already fully client-side, test your pages in Bing Webmaster Tools and ensure that the main content displays without JavaScript enabled. Use tools like Fetch and Render or Screaming Frog in " JavaScript disabled " mode to identify invisible areas.

What mistakes should be avoided in a multichannel strategy?

Do not assume that what works on Google works elsewhere. This is the classic error: a green GSC audit, zero investigation on Bing, and three months later discovering that 40% of the product catalog is not indexed in a secondary market.

Another pitfall: deploying a SPA (Single Page Application) without HTML fallback and relying on " progressive enhancement ". In theory, it's elegant; in practice, non-Google bots don't care. They want static HTML, not a promise of client-side hydration.

How can I check that my site is compatible with all engines?

Test your priority URLs in multiple environments: Google Search Console (of course), Bing Webmaster Tools, and if relevant, Yandex.Webmaster. Compare renders, crawl times, and indexing errors.

Use bot simulators (Screaming Frog, OnCrawl, Botify) with JavaScript disabled. If your strategic content disappears, you have a structural problem. No need to wait three months for Analytics data to confirm this.

• Deploy SSR or prerendering if actively targeting Bing, Yandex, or non-English-speaking markets.
• Test your pages in Bing Webmaster Tools and Yandex.Webmaster, not just GSC.
• Check rendering without JavaScript enabled (Screaming Frog, browser text mode).
• Monitor indexing performance across all strategic engines, not just Google.
• Plan HTML fallbacks for critical content (products, articles, landing pages).
• Document technical choices and trade-offs related to JS rendering in your project specs.