grafana/k6 · error

evaluating scroll offset

Error message

evaluating scroll offset: %w

What it means

Raised in screenshotElement when evaluating the inline JavaScript expression `() => { return {x: window.scrollX, y: window.scrollY};}` via Runtime.evaluate fails. The scroll offset is needed to convert the element's viewport-relative bounding box into document coordinates for clipping. This fires when the JS evaluation is rejected — most commonly because the frame's execution context was destroyed by a navigation, the page is closing, or the CDP session is broken.

Solutions

1. Avoid navigating or reloading the page concurrently with the screenshot call
2. Retry the screenshot after the page has finished loading (waitForNavigation/waitForLoadState first)
3. Verify the element is still attached to the DOM before screenshotting
4. Inspect the wrapped CDP error for the exact evaluation failure reason

When it happens

Trigger: Thrown at internal/js/modules/k6/browser/common/screenshotter.go:324 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of grafana/k6@3fcf5388d7 (2026-08-18). Data as JSON: /api/errors/9dfb7c27ca2afc34. Report an issue: GitHub.

Appendix: source

Thrown at internal/js/modules/k6/browser/common/screenshotter.go:346

		err = h.waitAndScrollIntoViewIfNeeded(h.ctx, false, true, opts.Timeout)
		if err != nil {
			return nil, fmt.Errorf("scrolling element into view: %w", err)
		}
		bbox, err = h.boundingBox()
		if err != nil {
			return nil, fmt.Errorf("node is either not visible or not an HTMLElement: %w", err)
		}
		if bbox.Width <= 0 {
			return nil, fmt.Errorf("node has 0 width")
		}
		if bbox.Height <= 0 {
			return nil, fmt.Errorf("node has 0 height")
		}
	}

	scrollOffset, err := h.Evaluate(`() => { return {x: window.scrollX, y: window.scrollY};}`)
	if err != nil {
		return nil, fmt.Errorf("evaluating scroll offset: %w", err)
	}

	var returnVal Position
	if err := convert(scrollOffset, &returnVal); err != nil {
		return nil, fmt.Errorf("unpacking scroll offset: %w", err)
	}

	documentRect := bbox
	documentRect.X += returnVal.X
	documentRect.Y += returnVal.Y

	return s.screenshot(
		h.frame.page.session,
		documentRect.enclosingIntRect(),
		nil, // viewportRect
		format,
		opts.OmitBackground,
		opts.Quality,

View on GitHub (pinned to 3fcf5388d7)