Google’s Web Crawler Fakes Being “Idle” To Render JavaScript

SEO

By Chris Barnhart Last updated Jul 22, 2024

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In a recent episode of the Search Off The Record podcast, it was revealed that Google’s rendering system now pretends to be “idle” to trigger certain JavaScript events and improve webpage rendering.

The podcast features Zoe Clifford from Google’s rendering team, who discussed how the company’s web crawlers deal with JavaScript-based sites.

This revelation is insightful for web developers who use such methods to defer content loading.

Google’s “Idle” Trick

Googlebot simulates “idle” states during rendering, which triggers JavaScript events like requestIdleCallback.

Developers use this function to defer loading less critical content until the browser is free from other tasks.

Before this change, Google’s rendering process was so efficient that the browser was always active, causing some websites to fail to load important content.

Clifford explained:

“There was a certain popular video website which I won’t name…which deferred loading any of the page contents until after requestIdleCallback was fired.”

Since the browser was never idle, this event wouldn’t fire, preventing much of the page from loading properly.

Faking Idle Time To Improve Rendering

Google implemented a system where the browser pretends to be idle periodically, even when it’s busy rendering pages.

This tweak ensures that idle callbacks are triggered correctly, allowing pages to fully load their content for indexing.

Importance Of Error Handling

Clifford emphasized the importance of developers implementing graceful error handling in their JavaScript code.

Unhandled errors can lead to blank pages, redirects, or missing content, negatively impacting indexing.

She advised:

“If there is an error, I just try and handle it as gracefully as possible…web development is hard stuff.”

What Does This Mean?

Implications For Web Developers

• Graceful Error Handling: Implementing graceful error handling ensures pages load as intended, even if certain code elements fail.
• Cautious Use of Idle Callbacks: While Google has adapted to handle idle callbacks, be wary of over-relying on these functions.

Implications For SEO Professionals

• Monitoring & Testing: Implement regular website monitoring and testing to identify rendering issues that may impact search visibility.
• Developer Collaboration: Collaborate with your development team to create user-friendly and search engine-friendly websites.
• Continuous Learning: Stay updated with the latest developments and best practices in how search engines handle JavaScript, render web pages, and evaluate content.

See also: Google Renders All Pages For Search, Including JavaScript-Heavy Sites

Other Rendering-Related Topics Discussed

The discussion also touched on other rendering-related topics, such as the challenges posed by user agent detection and the handling of JavaScript redirects.

The whole podcast provides valuable insights into web rendering and the steps Google takes to assess pages accurately.

See also: Google Renders All Pages For Search, Including JavaScript-Heavy Sites