Do these 3 things before closing this tab:
1Repair Windows errors before they cause bigger problems2Fix the driver behind crashes, sound loss and screen glitches3Clear out junk files and repair common Windows errorsTo capture an entire page with BackstopJS, set the scenario’s selectors property to ["document"]. The document selector targets the full document; viewport captures only the currently configured screen area. BackstopJS defaults to document when selectors is omitted, but writing it explicitly makes the full-page intent clear.
Configure a full-page scenario
A BackstopJS configuration needs at least one viewport and one or more scenarios. Each viewport has a label, width, and height; each scenario needs a label and URL. This minimal CommonJS configuration captures a local page across the full document:
module.exports = {
id: "my-project",
viewports: [
{ label: "desktop", width: 1280, height: 800 }
],
scenarios: [
{
label: "home full page",
url: "http://localhost:3000/",
selectors: ["document"]
}
]
};Save the configuration in the location expected by your BackstopJS project, then run its commands from that project. Change the URL to the page under test and configure viewports for the screen sizes relevant to your users. The official BackstopJS documentation describes document as the full-document target and viewport as the current configured viewport.
Choose the capture target
selectors: ["document"]captures the entire document and makes the full-page requirement explicit.selectors: ["viewport"]limits the capture to the current viewport dimensions.- If
selectorsis omitted, BackstopJS usesdocumentby default.
Full-page here means the document target, not a guarantee that every image, animation, or asynchronously loaded section is ready. Configure readiness and stable test data where the page needs them.
#1 Best Overall
- Read Before You Buy — No Video Output: These adapters support charging and USB 2.0 data transfer, but cannot transmit video signals. Except for standard USB webcams (which use USB data only), they are not compatible with HDMI/DisplayPort cables, video-capable USB-C hubs, or docking stations with video output.
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Wait until the page is ready
BackstopJS documents three readiness options for client-rendered or Ajax content. Choose the condition that actually signals the content your comparison depends on:
readySelector: wait for a known selector to appear in the DOM.readyEvent: wait for the application to log a chosen message to the console. Your app must emit it only after the required content is ready.delay: wait for a specified duration. The guide’s one-second example illustrates the option; it is not a universal timing recommendation.
For dynamic pages, stable fixture data or static stubs are preferable when practical. A fixed delay can be less reliable when load times vary, while a readiness condition tied to the content under test gives the capture a clearer signal.
Rank #2
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Set up interactive or authenticated pages
Use onBeforeScript to establish browser state such as cookies before the page is captured. Use onReadyScript for UI changes after readiness conditions, such as clicking or hovering. BackstopJS also documents importing cookie files through its default onBefore script. Set up only the state needed to reproduce the target page consistently.
Handle repeated selectors and dynamic regions
Multiple matching elements
When a CSS selector matches multiple elements, BackstopJS captures the first match by default. Set selectorExpansion: true to capture every match; with expansion enabled, expect can check the expected number of matches.
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Unstable content
For content that changes unpredictably and makes comparisons noisy, BackstopJS offers hideSelectors and removeSelectors. Hiding an element keeps its layout flow; removing it deletes it from the DOM before capture. These choices alter what the visual comparison observes, so use stable test data first where feasible and hide or remove content only when excluding it fits the purpose of the test.
Create and update visual baselines
- Configure the scenario URL, viewport, readiness behavior, and
documentselector. - Run
backstop referenceto create the reference images. - Run
backstop testto capture test images and generate the comparison report. - Inspect the report. Run
backstop approveonly when the changed images should become the accepted references.
Approval promotes changed images from the latest test batch into the reference collection; it is not a substitute for reviewing whether a visual change is intended.
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Troubleshooting full-page captures
- Only the visible screen is captured: check that the scenario uses
selectors: ["document"], not["viewport"]. - The capture misses content rendered later: add a
readySelectoror an app-emittedreadyEventthat corresponds to the required content. Use a delay only when an appropriate fixed wait is sufficient. - Images or page regions vary between runs: stabilize test data where possible. If a changing region should not be compared, decide whether to hide it while preserving layout or remove it from the DOM.
- A selector capture includes only one of several matches: enable
selectorExpansion: trueif every match should be captured, and useexpectto validate the expected count. - A new test image differs from its reference: inspect the report before approving. Approve only if the new appearance is the baseline you intend to keep.
Or skip the browser setup
If you need a screenshot from an API rather than a BackstopJS visual-regression workflow, ScreenshotNeo returns a screenshot or PDF from one GET request. Its capture can accept cookie banners and remove known consent platforms, newsletter popups, and chat widgets before the shot; those steps can be turned off. Bot checks, blank pages, timeouts, failed loads, and cache hits are not billed, and the response identifies the page verdict and billing status in headers. An MCP server provides take_screenshot, get_page_info, and capture_pdf for AI agents and other MCP clients.
For example, with an API key:
curl -G "https://api.screenshotneo.com/v1/shot" -d access_key=YOUR_API_KEY --data-urlencode url=https://stripe.com -o shot.webpSee the ScreenshotNeo API documentation for parameters and response details. The free plan includes 1,000 screenshots per month with no card; paid plans start at $5 for 3,000. Sign up for ScreenshotNeo’s free plan.
Frequently Asked Questions
Does BackstopJS default to a full-document capture?
Yes. Its documented default for an omitted selectors property is document.
Best Value
- 5-in-1 Connectivity: Equipped with a 4K HDMI port, a 5 Gbps USB-C data port, two 5 Gbps USB-A ports, and a USB C 100W PD-IN port. Note: The USB C 100W PD-IN port supports only charging and does not support data transfer devices such as headphones or speakers.
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- What You Get: Anker 332 USB-C Hub (5-in-1), welcome guide, our worry-free 18-month warranty, and friendly customer service.
Can I capture every element matched by a selector?
Yes. Set selectorExpansion: true; you can use expect to validate the expected number of matches.
Quick Recap
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