Title changes after JS: which one does Google use?

When JavaScript rewrites your title tag after load, Google may use either version. Find pages where the title changes after render and see if it matters.

audited sites affected

What it means

The title tag in the initial HTML response differs from the title rendered after JavaScript execution. The server emits one value and JavaScript updates it to another, so the raw HTML and the rendered DOM disagree.

Why it matters

Googlebot parses raw HTML first and queues the page for rendering. If it indexes before JavaScript runs, it captures the initial title. That means the title in the index may not match what users see, and AI agents that rely on the initial HTML may read the wrong title.

How to fix it

Set the title server-side so the initial HTML contains the final title value.
Verify the title in the raw HTML response, not just in rendered output.
If you must set the title with JavaScript, ensure it runs synchronously and does not depend on user interaction.

Example

Before — HTML (before vs after JS)

<!-- Raw HTML -->
<title>Loading… | Acme</title>

After — HTML (before vs after JS)

<!-- After JS renders -->
<title>Red Running Shoes | Acme</title>

The raw HTML shipped a placeholder title that JS later replaced. Google may index the pre-render title — render the real one server-side.

When it's not a problem

This is a false alarm if the JavaScript title update is fast, deterministic, and always produces the same value. It is also fine when the initial and rendered titles are close enough that the difference does not affect search visibility or AI-agent extraction.

How Crawlinx detects it

We compare the <title> in the raw HTML against the title after JavaScript renders. When they differ, we report both — Google can index either, so a placeholder in the raw HTML is a risk.

How common is it?

Not yet observed in our audit sample. We publish this explainer because the check runs on every crawl; once an audited site trips it, this page will break the issue down by platform, gatekeeper, vertical and country.

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