This is the crux of the article. When the technical structure of an IR site comes up, internally or in a vendor meeting, two claims appear. Neither squares with the published observations.
4-1. Claim A: "Google renders it, so we are fine"
The basis for this claim is that Google states officially that it renders JavaScript. That statement is itself correct. The problem is that "Google" is not one crawler.
In the 41-day experiment, what reached the far side of the JavaScript links were two Google user agents. So far, this matches claim A. The breakdown changes the picture. Of the 293 pages in the JavaScript group, GoogleOther reached 142 (48%), while Googlebot, the crawler that builds the search index, reached 7 (2%).
The author writes it plainly: the 66% and 48% figures for GoogleOther say nothing about whether those pages appear in Google search. What bears on visibility in search is the Googlebot side, and that figure is 2%.
Being rendered and being on the path into the search index are separate events. Counting everything that calls itself Google as one number risks a false read of how far retrieval reached. If a vendor supplies your logs, whether Googlebot and GoogleOther are counted separately is worth checking before anything else.
4-2. But do not let the 2% travel on its own
In the same experiment, Googlebot reached 35 of the 748 pages in the HTML link group (5%). The 2% in the JavaScript group is a figure to be read alongside the 5% in the HTML group. The author himself reads GoogleOther's roughly 14-to-1 lead over Googlebot on HTML pages as a by-product of crawl budget on a new domain, and states that the Googlebot share would be higher on an established site.
So what this experiment supports is not "Googlebot cannot execute JavaScript." What it supports is that under these conditions the reach of the crawler that builds the search index was thin to begin with, and thinner still on the JavaScript side. Capability is one question; whether your own pages are actually receiving that processing is another.
There is supporting material as well. In the same experiment, GoogleOther's discoveries on the JavaScript side lagged the HTML side by 18% to 27%, because a rendering queue and an execution step sit in between. Reach was uneven too: one category got to 52 pages while two others sat at a single page for weeks. Some branches never come up in the queue, the author writes. Brought back to IR, the question becomes whether the pages you cannot afford to have retrieved late are sitting on the side that tends to be late.
4-3. Claim B: "AI cannot read JavaScript"
The assertion in the opposite direction is just as precarious.
First, some do execute it. In the observation published on December 17, 2024, Gemini and AppleBot are reported to execute JavaScript.
Second, a limited counter-example is reported. In an experiment report published by EdgeComet on January 15, 2026 and updated on February 17, 2026, log observation on a new domain found that ChatGPT-User retrieved raw HTML documents alone, while for GPTBot the report observed one AJAX request among several hundred requests. The report summarizes this as showing that it can execute but rarely does. Interested-party status and limits: EdgeComet is a vendor providing rendering, and the article closes with a route into its own service. It is an in-house experiment on a single new domain, and the author states explicitly that it is not put forward as a final conclusion. It is properly treated as a limited counter-example to the proposition that AI never executes JavaScript, and it does not support "it executes, so you can relax."
Third, the zero for PerplexityBot cannot be given a meaning from this experiment alone. In period 1 it fetched nothing beyond the homepage and robots.txt, and its first arrival at a hierarchy page was on day 40. You cannot say that something which did not come to fetch is unable to execute.
Fourth, the question was never "are you using JavaScript." Formats other than HTML, such as JSON inside the initial HTML response, can also be picked up. What is being asked is whether the information you need, and the route to it, are inside what comes back first.
4-4. A crawl record does not show that something was used in an answer
The author of the 41-day experiment states explicitly that crawl logs show whether something could be reached, not whether it was indexed. The December 2024 observation adds that asking about recent documentation does not always produce an immediate retrieval record, pointing to possible reliance on caches or trained data. Retrieved is not indexed, and indexed is not used in an answer. That is why the measurement in §10 looks at both the retrieval side (logs) and the answer side (questions put to AI).
4-5. An asymmetry that shows up after a redesign
Period 2 contains an observation that bears directly on running an IR site. After the links were rewritten into HTML, GPTBot retrieved 250 pages within two days, Bingbot added 212, and Meta-ExternalAgent also swept the site by day 41. For some crawlers, rediscovery was observed within a short period after the rewrite to HTML. Not every crawler came back the same way, however.
ClaudeBot, meanwhile, kept re-fetching after the rewrite without picking up a single newly linked page, and Amazonbot had left six days before the rewrite. Google was slowest: as of day 41, Googlebot had visited one page among the rewritten categories and GoogleOther none.
This is an observation of one site over 41 days, not a general law. It does give you a way to separate a retrieval lag from other causes when an AI answer feels stale right after a redesign.
4-6. So what can be written?
Placing your key information, and the links that lead to it, in an initial HTML response that can be retrieved without assuming JavaScript execution is consistent with the observations currently available.
Nothing beyond that. In particular, as to what percentage this improves the accuracy of AI answers or the way they cite you, within the scope of this review, we could not confirm a figure. This article also does not specify an implementation method. There are several, and the choice depends on the site's build and on your contract with your vendor. What has to be decided is not the method; it is that you measure the current state first.