Google’s Crawler Now Understands JavaScript: What Does This Mean For You?

Googles Crawler Now Understands JavaScript: What Does This Mean For You? image googlebot crawler javascript indexing illustration 300x78Last week Google announced a significant change to their crawler’s behaviour. The “Googlebot” finally has the ability to interpret JavaScript, the last remaining core construct used to create and manipulate content on web pages (HTML and CSS being the other two).

In an official post on their Webmaster Central Blog, Google shared that when it first began crawling sites, the Internet was a very different place. Sophisticated JavaScript wasn’t really commonplace; instead, it was used to “make text blink”.

The Internet and the way we use it evolved over time and JavsScript’s unique ability to essentially reach into web pages and pro-grammatically manipulate content became increasingly recognized. For the past decade or so, web pages have become dependent on the ability to use JavaScript, and although it’s best practice to have them degrade gracefully so that users who disable JavaScript can still use the page, to say that that doesn’t always happen is an understatement.

Given our dependence on JavaScript and other technologies that have been developed with JavaScript as a foundation, It’s a little surprising to me that Google, the dominant search engine worldwide, waited this long to index JavaScript. The reason they hadn’t done this earlier, presumably, is because JavaScript has the potential to confuse search engine spiders: it can manipulate content, lead to other pages, cloak links and content, etc.

Tests conducted a couple of years ago have demonstrated that Google has had some (extremely limited) capacity to process JavaScript. Given this partial support, it stands to reason that the Googlebot still isn’t able to process all JavaScript, just more of it. Indeed, the Webmaster Central Blog post does admit “sometimes the JavaScript may be too complex or arcane for us to execute”.


So what are the implications crawlers of being able to execute JavaScript for the state of SEO?
Let’s take a look at some of the changes you’re likely to see on Google and which sites they’ll have the biggest effect on.

1. Better Flow of Link Juice

It may be a little obscure, but some websites use JavaScript links frequently within their design. Entire navigation menus are sometimes fully reliant on JavaScript. The ability to parse these links will result in better “link juice” distribution. This will be beneficial for most pages, but it may dilute the value of some (imagine a page that has an overwhelming excess of outbound JavaScript links).

2. Poor Load Times

The use of excessive JavaScript is rampant and, often times, a browser has to make a significant quantity of additional requests and spend time downloading this JavaScript. Now that the Googlebot has to do this too, many sites’ load times in the eyes of Google are likely to increase. To see if you’re affected log in to your Google Webmaster tools and check your “Crawl Stats” graph over the past few months.

3. Higher Crawler Abandonment Rates

Since the Googlebot won’t be capable of processing extremely complex JavaScript, it might give up on indexing pages that use a lot of JavaScript to produce an unconventional user experience—you know, the sort of sites you see featured on Awards every now and again.

4. Innovation in Black Hat SEO

This change on Google’s behalf opens the doors to new ways to trick the Googlebot into indexing content it doesn’t want to. For instance, after analysing the limitations of the Googlebot’s ability to read JavaScript, it’s likely that sooner or later, someone will develop new ways to cloak content (show real visitors one thing while showing the Googlebot something else).

Of course, the above-mentioned are predictions. We can’t forget that SEO is, at its core, reverse engineering. A more accurate understanding over what Google’s really doing will come from testing and checking your data.

The engineers over at Google mentioned that they’ve been rolling out the ability to read JavaScript over the past “few months”, so if you’ve seen changes in your Webmaster Tools in the February—May 2014 window let us know in the comments!


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