JavaScript

Describes GLLmolfar 0.9.35current release · checked 8 Nov 2026

What a page says before and after its JavaScript runs. For every rendered page: words in the served HTML and after rendering, the fields JavaScript changed, internal links that exist only after it, and images that appear only when the page is scrolled.

Where: Site › All pages › More columns… › JavaScript
Mode: Pro
Built from: Each page's served HTML and, when it was rendered, the rendered page
Changes: Live during a crawl

On the screen

The JavaScript column set with one of its filters, a page picked, and the inspector's Source pane showing the lines JavaScript added.

The JavaScript column set of GLLmolfar on a 500-page crawl of getlooploop.com with every page rendered, and the lines JavaScript added to the home page — real screenshotgetlooploop.com serves its text in the HTML, so the word counts barely move; what JavaScript adds on every page is two internal links (the filter shows all 500) and an analytics snippet.

Which pages are rendered

Two settings in Settings › Crawling decide it. JavaScript rendering: Off · raw HTML only, Auto · render pages with little text (the default), or All pages (slower). Read a rendered page: when the page stops changing (faster), or when the network is quiet too, for pages that load content late. A page that was not rendered has nothing to compare, so most of this column set is empty for it.

Columns

Column	What it shows
Words (raw HTML)	Words in the HTML as the server sent it.
Words	Words in the page as it was read: after JavaScript when it was rendered.
JS change, %	How much of the rendered text JavaScript added (negative when it removed text). 0 for a page that was not rendered.
Changed by JS	Which of canonical, meta robots, title, H1 and description differ after JavaScript, and +N links.
Links only after JS	Internal links found in the rendered page and not in the served HTML.
Images after scrolling	Images whose address appears only when the page is scrolled, with no fallback in the served HTML. The tip lists examples.
JS	Whether the page was rendered.

Filters

Filter	Which pages
Rendered with JavaScript	Pages that were rendered.
Text appears only after JavaScript	Under 100 words in the served HTML, 100 or more after rendering.
JavaScript changes the text by over 20%	The word count moved by more than a fifth.
Not rendered	Pages read from the served HTML only.
Canonical changes after JavaScript	The canonical in the rendered page differs from the served one.
Meta robots changes after JavaScript	The robots directives differ.
Title changes after JavaScript	The title differs.
H1 changes after JavaScript	The H1 differs.
Description changes after JavaScript	The meta description differs.
Internal links only after JavaScript	At least one internal link exists only in the rendered page.
Images that appear only after scrolling	At least one image found only after the scroll pass, without a fallback in the served HTML.

Images that appear only after scrolling

After a rendered page has been read, the app scrolls it to the bottom in steps (at most 30 screens and 3 seconds) and records the image addresses that exist only after the scroll. Reading the page itself is unchanged: the text, links and fields come from before the scroll.

Only rendered pages are scanned. With rendering on Auto, a page with enough text in its HTML is not rendered and has no value here.
Native loading="lazy" is fine: the image and its address are in the HTML from the start. Those are counted apart (Native lazy images in the detail) and never flagged.
An image is not flagged when the served HTML carries its address anyway, in a <noscript> image, a src or a srcset.
The crawl does not download images: it records that an address is in the page, not whether the picture loads.

Settings › CrawlingSettings › Crawling: request speed, connections, the user agent, the timeout, robots.txt, a pause at a CAPTCHA, JavaScript rendering and service pages.All pages (Internal)The All pages tab, called Internal in Pro mode: every crawled URL in one table, with filters, search, column sets, an overview panel and a page inspector.URL auditSite › URL audit: one page checked without a crawl — status, speed, JavaScript, page map, failed checks, accessibility, robots.txt, headers and screenshots.Links (internal linking table)The Links column set: inlinks, unique inlinks, click depth, Link score (internal PageRank) and each page's share of the site's internal weight.