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Javascript Rendering: Common JS Rendering Issues for Websites

If you use JavaScript on your internet site—and 98.8 percent of web sites do—then knowledge how JavaScript renders and why it’s vital for your website is vital.


Unrendered or poorly rendered JavaScript could have untold affects for your internet site. It may even pass thus far as to effect SEO if Google JavaScript rendering can’t take area as it’s intended to.

The truth is, JavaScript rendering problems will occur. So understanding why they occur and how to deal with them may be the distinction among a poorly rendered internet site or an highest quality consumer (and crawlbot) enjoy.

In this put up, I’ll explain what rendering JavaScript is and why it’s vital. My team at NP Digital can even offer an evaluation of three SaaS manufacturers, consisting of common JavaScript rendering errors. Finally, I’ll offer a rundown of the maximum common JS rendering errors and the way you may deal with them.

We have lots to cowl, so permit’s leap right in!

Key Findings On JavaScript Rendering

JavaScript rendering is crucial for website usability and capability, impacting whole sections or pages if left unrendered for customers.

NP Digital analyzed three websites to example capacity problems with JavaScript Rendering

Zoom (Brand #1) Analysis:

Analysis of Zoom’s internet site exhibits variations among uncooked HTML and rendered HTML, together with missing hreflang attributes in uncooked HTML.

Instances like lacking H1 tags in raw HTML can effect SEO and restrict internet site performance.

Asana (Brand #2) Analysis:

Similar to Zoom, Asana faces troubles like differing page titles in raw HTML and rendered HTML.

Asana has numerous pages with blocked JavaScript assets, but this could be without problems constant via updating the robots.Txt record.

Neil Patel (Brand #3) Analysis:

Neil Patel’s internet site additionally exhibits attributes displayed in rendered HTML but not in uncooked HTML.

There turned into a minimum impact from blocked JavaScript documents, showcasing powerful control of this not unusual trouble.

Why JavaScript Rendering Is Important

JavaScript rendering is important from views.

First, from a user perspective, JavaScript rendering is vital for internet site usability and functionality. Depending on what elements are loaded the use of JavaScript, complete sections or even pages or your internet site can be inoperable if JavaScript is left unrendered.

If JavaScript isn’t rendering for users, then it’s truly now not rendering for search engine crawlbots. This way that Google cannot index or rank your website on SERPs.

This could have enormous implications for search engine optimization, and it’s a massive reason why JavaScript search engine marketing wishes to be part of your usual search engine optimization and advertising and marketing approach.

How Brands are Using JavaScript Rendering

JavaScript is used so extensively that it could be difficult to pinpoint what on a website is HTML and what is JavaScript. To show you simply how commonplace JavaScript is on websites—and why know-how JavaScript rendering is important—my group at NP Digital has assessed 3 SaaS manufacturers.

Using Screaming Frog and source code, we’ve dug into the overall web site breakdown of URLs to decide simply how many are using JavaScript. We’ve also analyzed a web page or two from each web page to reveal you the ability effect that poorly rendered JavaScript could have on search engine optimization.

Before we dive in, even though, here’s a crash route in HTML rendering and JS rendering.

We’ll be discussing two styles of HTML formats in this put up. The first is uncooked HTML and the second one is rendered HTML.

Raw HTML: The unique version of HTML on a internet site before JavaScript has loaded.

Rendered HTML: The HTML this is visible after JavaScript has loaded.

Now you will be asking, in which and while does rendering JS take region?

There are two possibilities. The first is server-aspect rendering, and that is accomplished on the website’s server before being despatched to the patron (i.E. User browser). This is the most not unusual rendering choice as it offers a smoother revel in for the person.

The 2nd choice is client-facet rendering, in which the user’s web browser ought to render the JavaScript earlier than the internet site fully hundreds. This can reason lag and is not endorsed for most web sites.

Finally, even as we won’t discuss is just too heavily, it’s additionally useful to understand how HTML is study through computer systems (including crawlbots). The record object version (DOM) is the shape of an HTML record. The HTML factors are stored break free the JavaScript elements, as shown beneath:

This is carried out for lots motives. For builders, it’s easier to pinpoint mistakes and make changes to the HTML or the JavaScript as wanted. For internet site rendering purposes, this ensures that HTML elements are nonetheless loaded in their uncooked version even supposing JavaScript doesn’t render.

Now which you have a few heritage know-how, allow’s begin our analysis of 3 SaaS brands: Zoom, Asana, and Neil Patel.

Brand #1: Zoom

The first SaaS emblem we analyzed was Zoom, a cloud-based totally video conferencing provider.

Using Screaming Frog, the NPD group ran a scrape of the whole U.S. Version of the Zoom website to peer how JavaScript may be impacting their website. Screaming Frog is first rate for figuring out where JavaScript indicates up in the rendered HTML that Google cares approximately.

Right away, we can see a distinction inside the way the hreflang attribute is handled in the original HTML as opposed to the rendered HTML. More particularly, hreflang is lacking from the authentic HTML (lines 39 through fifty six):

Assuming rendering in JavaScript occurs well, this is not in all likelihood to have an impact on the performance of the website. However, by means of now not consisting of the hreflang characteristic inside the uncooked HTML, there may be the capability that this information is not exceeded to Google.

Let’s have a look at some other instance where raw HTML and rendered HTML differ:

In the above instance, we will see that the H1 tag is well rendered with JavaScript. However, for the reason that H1 tag isn’t always protected inside the raw HTML, there is the capability for Google to miss this critical tag if the web page changed into now not well rendered.

Instances like this could have major impacts on search engine optimization and prevent website performance.

It’s not continually the case that an crucial assets is lacking entirely from the raw HTML, however as a substitute, it can be one of a kind from what the rendered HTML is displaying. In the below instance, the identify tag in the raw HTML is “Loading” at the same time as the title tag in the rendered HTML is “Zoom Learning Center”:

This is an example wherein JavaScript is updating the web page identify dynamically, but if JavaScript didn’t render then Google might now not index the proper web page identify.

One component to note is that JavaScript errors are not unusual, and that they don’t typically have a large effect on page rendering. We can see this with the aid of looking at the source code and seeing that each one applicable information we’d count on to see on a web page—mainly HTML tags—are seen.

This doesn’t suggest that JavaScript mistakes can’t be elaborate for other motives, though.

Just take, for instance, Zoom’s creator pages like this one for Janine Pelosi:

In this example, the raw HTML doesn’t have the picture used above however the rendered HTML does. This method if the traveler’s browser doesn’t render JavaScript, they may no longer be seeing everything you show for your web site.

From a credibility viewpoint, that’s a loss.

How can a traveler see your website as credible and authoritative if they can’t positioned a face to a name? The equal can be stated for imagery and symbols that your website displays somewhere else, like at checkout.

Overall, the above troubles are not causing troubles for page rendering. So while some on-page elements or information won’t be available to Google crawlbots within the uncooked HTML, they will get them within the rendered HTML.

One major problem that’s not precise to Zoom is a website blocking .Js documents inside the robots.Txt report. This can prevent Google crawlbots from crawling, rendering, and indexing those documents which might be adverse for your SEO ranking.

Here’s a listing of all of the JavaScript URLs with blocked sources on Zoom:

If this isn’t corrected, it can have most important influences on ratings.

Brand #2: Asana

The 2d SaaS emblem we tested changed into Asana, a work and assignment control platform.

Like Zoom, Asana leverages JavaScript throughout their website. We see a number of the same troubles on Asana as on Zoom, together with differing web page titles on uncooked HTML versus rendered HTML.

This isn’t a primary difficulty, assuming there’s nothing blocking the pages from rendering as they have to.

However, much like with Zoom, Asana does have numerous pages with blocked JavaScript assets:

The right news is that this is an smooth restoration. The robots.Txt document simply needs to be updated to make certain that no critical resource documents (i.E. JavaScript) are being blocked. Once the blocks are eliminated, the documents can be rendered to each internet customers (i.E. Consumer browsers) and Google crawlbots.

Don’t need to wait the weeks or months it may take for Google to recrawl your web page?

Once you’ve unblocked your JavaScript files, you can ask Google to recrawl your URLs. This will ensure your formerly non-indexed or poorly indexed pages are recrawled, rerendered, and reindexed for SERPs.

Brand #three: Neil Patel

I couldn’t possibly examine SaaS web sites that use JavaScript with out throwing my own website online, neilpatel.Com, into the mixture!

Similar to Zoom and Asana, we see a number of attributes (e.G. Hreflang, content material) displayed within the rendered HTML but not inside the uncooked HTML:

The content is well loaded, so these are unlikely to be impacting Google crawlability. However, if the rendered HTML did not show the content due to blocked JavaScript files, for example, then Google can be missing (i.E. No longer indexing) crucial content material.

Speaking of blocked JavaScript documents, although, Neil Patel simplest has three URLs impacted by way of the not unusual difficulty:

This is something we noticed across all 3 manufacturers to various levels, even though Neil Patel does a first-rate task of minimizing the chance via decreasing the range of blocked JavaScript files.

My team did locate one issue that we’re working quick to solve, and that’s making sure our JavaScript hyperlinks render correctly.

What are JavaScript hyperlinks?

These are links created in JavaScript, both rather than or similarly to, in HTML.

If the JavaScript hyperlinks don’t render, then the inner link fine and page authority will now not be surpassed to the focused URL. After all, if the hyperlink can’t render then Google can’t crawl!

Common Javascript Rendering Issues and How to Address Them

We have tested 3 popular SaaS web sites and feature across a few JavaScript rendering troubles. So what are the maximum commonplace of these problems and how are you going to deal with them?

Blocked .Js Files in Your robots.Txt File

If I had to choose simply one JavaScript rendering trouble to awareness on, it might be blocked JavaScript resources inside the robots.Txt file.


A blocked JavaScript useful resource is one which has no risk of rendering, whether for the user or Google crawlbots. While there may be reasons to dam some sources within the robots.Txt report, it’s something you should avoid on every occasion possible.

The other purpose I like to name interest to this JavaScript rendering issue is because it’s such an smooth fix!

You or your internet site administrator absolutely need to update the robots.Txt record to do away with resource blocks. This just takes a touch bit of knowledge of robots.Txt files. Once completed, you could ask Google to recrawl your URLs.

Conflicting Directives

There are some ways to at once speak with seek engine crawlbots to your HTML code. These are known as directives, and a few famous examples of them are the “noindex” and “nofollow” tag attributes.

The noindex directive tells crawlbots not to index the web page, while the nofollow directive tells crawlbots not to skip hyperlink juice from the cutting-edge URL to the related URL.

A not unusual JavaScript rendering issue is conflicting directives. This way that the uncooked HTML consists of one or greater directives that the rendered HTML doesn’t. We saw this on Zoom, as proven in the picture under:

When this occurs, neither the non-rendered web page nor the rendered JavaScript page might be indexed. It may additionally motive a timeout errors, which is likely to appear in any website performance reports you run.

Fortunately, the fix for that is additionally simple.

If you need to ensure that your page is noindexed with out growing a JavaScript timeout mistakes, then ensure the noindex directive is protected in the rendered HTML as well. If as a substitute you wish the web page to be indexed, then make certain the directive is removed from each the uncooked HTML and rendered HTML.

Non-Renderable JavaScript Links

Just like JavaScript documents won’t constantly render, the same can be said of JavaScript hyperlinks.

These links could have many functions, even though maximum of them name to associated JavaScript files (e.G topic documents) or plugins.

It’s not uncommon for documents to be deleted or plugins to be deactivated over the life of your website. So because of this, you very probably have non-renderable JavaScript links.

In many instances, like most JS rendering mistakes, those won’t have an effect on average website overall performance. However, you ought to know which hyperlinks are non-renderable and do away with them on a regular foundation to avoid script bloat.


What is server-facet rendering?

Server-facet rendering is JavaScript rendering that happens on the internet site server. The uncooked HTML is converted into rendered HTML earlier than it’s sent to the client (e.G. Consumer browser). This is the other of patron-aspect rendering, where uncooked HTML is sent to the customer after which transformed into rendered HTML.

How does server-facet rendering work?

With server-aspect rendering, the customer contacts the server via an HTTP connection. The server then fetches required records (either from the database or third parties) and creates a rendered HTML record which it then sends to the purchaser. This method the facts being sent from server to consumer is complete and does no longer require similarly rendering at the endpoint.

Can google move slowly JavaScript?

Google can not crawl JavaScript, but it is able to render JavaScript. This manner it can remodel JavaScript into rendered HTML that’s crawlable by means of Google crawlbots. Once that is accomplished, the crawlbots can continue to move slowly and index your webpage as they might otherwise.


Rendering JavaScript is some thing that lots of us have in no way given a thought. We take as a right all of the work involved in loading a fully functioning web site.

You now recognise, though, that JavaScript rendering isn’t always always a super technique. And whilst it could no longer have substantive influences to your website’s performance, it may certainly impact such things as SEO.

Even famous SaaS brands—like Zoom, Asana, and Neil Patel—have JavaScript rendering errors to deal with. The desirable news is, you too can locate your site’s JS troubles and ensure they are fixed before you start to see fundamental affects in your website.

Do you have questions about not unusual JS rendering troubles? Let us recognise in the comments below.

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