grafana/k6 · error

converting result (%v of type %t) to border: %w

Error message

converting result (%v of type %t) to border: %w

What it means

offsetPosition() converts the result of injected.getElementBorderWidth into struct{Top, Left float64}. This error means the eval result did not deserialize into that {top,left} shape. Note the message itself contains a formatting bug: %t (the bool verb) is used for the result argument, so the rendered type is garbage like %!t(string=...).

Source

Thrown at internal/js/modules/k6/browser/common/element_handle.go:438

func (h *ElementHandle) offsetPosition(apiCtx context.Context, offset *Position) (*Position, error) {
	fn := `
		(node, injected) => {
			return injected.getElementBorderWidth(node);
		}
	`
	opts := evalOptions{
		forceCallable: true,
		returnByValue: true,
	}
	result, err := h.evalWithScript(apiCtx, opts, fn)
	if err != nil {
		return nil, err
	}

	var border struct{ Top, Left float64 }
	if err := convert(result, &border); err != nil {
		return nil, fmt.Errorf("converting result (%v of type %t) to border: %w", result, result, err)
	}

	box, err := h.BoundingBox()
	if err != nil {
		return nil, fmt.Errorf("finding offset position: %w", err)
	}

	if box == nil || (border.Left == 0 && border.Top == 0) {
		return nil, ErrElementNotVisible
	}

	// Make point relative to the padding box to align with offsetX/offsetY.
	return &Position{
		X: box.X + border.Left + offset.X,
		Y: box.Y + border.Top + offset.Y,
	}, nil
}

View on GitHub (pinned to 93accf6570)

Solutions

1. Retry after re-locating the element
2. Upgrade k6 so the injected script and Go module match
3. Avoid the offset path: omit `position` to click the element center
4. Report the %t formatting bug upstream (should be %T) when filing any reproduction

Example fix

// before
await handle.click({ position: { x: 10, y: 10 } }); // converting result ... to border

// after
await handle.click(); // center click, avoids getElementBorderWidth path

// Pre-check the element still exists before an offset click
const attached = await handle.evaluate((el) => el.isConnected);
if (!attached) throw new Error('element detached');

try {
  await handle.click({ position: { x: 10, y: 10 } });
} catch (e) {
  if (String(e).includes('to border')) {
    await handle.click(); // fall back to center click
  } else { throw e; }
}

When it happens

Trigger: click()/dblclick()/hover() with a `position` option (the offsetPosition path) when the border-width script returns undefined or a non-object — node is not an element anymore, execution context mismatch, or injected-script version skew.

Common situations: Offset clicks on elements in cross-origin iframes; stale handles; custom xk6 builds with mismatched injected script; also the %t verb makes diagnosing the real type harder.

Related errors

• finding offset position: %w
• element is not attached to the DOM
• getting document element: nil document
• clicking the checkbox did not change its state
• parsing check options: %w

AI-assisted analysis of grafana/k6@93accf6570 (2026-08-15). Data as JSON: /api/errors/06e7ef780ba77672. Report an issue: GitHub.