July 27, 2017

Can search engines read JavaScript?

We’ve all likely heard of JavaScript, some of us have a deep understanding of how the coding language works while the rest of us probably know enough to get by. As a company who provides technical SEO account management, it’s our job to not only understand JavaScript but also know how it will appear to search engines.

So, what if I told you that all of the work you have put in to a website’s functionality might actually be invisible to search engines? 

Okay maybe not completely invisible… But it’s certainly a lot more expensive to crawl.

A couple of months ago Alpha Digital had the opportunity to attend a Google conference where a spokesperson informed us that Google bots will crawl some JavaScript but it’s 30x more expensive to do so.

If you work in SEO then you’re likely aware of the fact that every website has a crawl budget which is responsible for how updated your site is on a regular basis. Meaning that, if you use up your crawl budget on bulky JavaScript, your site will probably run the risk of having less updates.

How much JavaScript can Google bots read?

In a recent update from Google we found out that Google does support the use of JavaScript when it’s being used to provide the following information;

  • Titles
  • Descriptions
  • Robots meta tags
  • Structured data (Schema)
  • Other meta data
  • Google will also naturally support AMP

Defining these attributes with JavaScript and other mark-up languages are sometimes preferred when defining certain aspects of a website such as Schema. However, main sections on the page, the areas containing the bulk of your optimised content, are much more readable if not blocked by scripts.

But what about other search engines?

While Google might be taking large strides to improve its ability to crawl JavaScript, it’s not the only search engine. Bing and Yahoo are also widely used in Australia and unfortunately, it seems like neither of these search engine bots have equal JavaScript crawlability in comparison.

This basically means that a website whose site functionality relies heavily on JavaScript, might actually be hindering the ability to appear in other search engine results. Something to look out for if your client is wondering why they’re on the first page of Google but not appearing till the 5th page on other search engines.

If you’re interested to see how your/client’s website looks without JavaScript we recommend using the Chrome JavaScript Switcher. If your site content disappears when you switch off JavaScript then maybe re-consider your SEO tactics or focus on other areas that are more likely to be visible to a search bot.


The main points to take away;

  • Google supports JavaScript, but is limited in ability and budget to crawl it
  • Other search engines still have a bit of catching up to do before they can safely say that they have the same functionality
  • If your site is rendered unusable without JavaScript then search engines might struggle to read the content

Remember, this kind of optimisation is only a small part of SEO. Search engines will also consider your engagement metrics, bounce rate, and user experience. All of which can be improved dramatically with highly engaging JavaScript functionality.

It’s up to yourself or your client to decide just how much search engine readability you would like to sacrifice for engaging interaction and usability.

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