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Low This Hint is of the lowest significance, and should only be addressed if there are not more serious issues which have not been handled. Issue This Hint represents an error or problem that needs to be fixed.

Meta Description modified by JavaScript

This means that the URL in question has a meta description that is different in the response HTML of the page, when compared with the rendered HTML.

Why is this important?

Google clearly state in their documentation that it is fine to use JavaScript to set or change the meta description:

Change title or meta description with JS

However, this doesn't mean that this is the optimal way to deliver page content to search engines.

The problem is that rendering webpages is a resource intensive task, and it takes significantly longer than simply grabbing source (response) HTML content.

This is why Google essentially crawl URLs in a two-stage process: their 'first look' is of the HTML response, then they render the page and have a 'second look' at the rendered HTML, then they update the index based on what they found in the rendered HTML.

Google rendering

As a result, URLs can and do enter the index initially based on this 'first look' (i.e. the HTML response) and there will be an indeterminate amount of time between this and the 'second look' (i.e. the rendered HTML).

So it is important that the HTML response contains all of the core elements as you want them to be included in the index, including the meta description.

If the meta description is being modified by JavaScript, then this implies that the 'correct' title is the one in the rendered HTML. However Google may index the page with meta description found in the HTML response, and it may take some time before they are able to render the page and update the meta description.

This becomes particularly important if the page content (and meta description) is changing all the time, you can easily end up in a situation where Google have the 'old' version indexed.

What does the Hint check?

This Hint will trigger for any internal URL that contains a different meta description in the response and rendered HTML.

Examples that trigger this Hint

This Hint will trigger for any URL that has a meta description in the <head> of the response HTML, which has a different value in the rendered HTML.

For example, if the response HTML looked like this:

<!doctype html>
<html lang="en">
<head>
<meta name="description" content="Never visit this page">
<meta name="robots" content="index,follow">
...
</head>
<body>...</body>
</html>

And the rendered HTML looked like this:

<!doctype html>
<html lang="en">
<head>
<meta name="description" content="Visit this amazing page">
<meta name="robots" content="index,follow">
...
</head>
<body>...</body>
</html>

How do you resolve this issue?

In general, it is not a good idea to rely on JavaScript for the core on-page elements, otherwise you may find that pages are getting indexed with the wrong data, or taking a lot longer to get indexed. Additionally, Google may not always be able to render pages correctly, or it may not be able to execute JavaScript at all.

The meta description is an important on-page element - you really want to have this available to Google on their first look of the page.

To resolve this issue, you would need to work with the development team to ensure that the meta description is present in the HTML response, and is not then changed by JavaScript during rendering.

Further Reading

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