grafana/k6 · error

extracting json value (remote object id: %v): %w

Error message

extracting json value (remote object id: %v): %w

What it means

Thrown by BaseJSHandle.JSONValue when the CDP call succeeded but parseConsoleRemoteObject cannot convert the returned remote object into a JSON string. The referenced value is not JSON-serializable from the protocol's perspective: functions, symbols, undefined, or objects the runtime refuses to serialize by value.

Source

Thrown at internal/js/modules/k6/browser/common/js_handle.go:208

}

// JSONValue returns a JSON version of this JS handle.
func (h *BaseJSHandle) JSONValue() (string, error) {
	remoteObject := h.remoteObject
	if remoteObject.ObjectID != "" {
		var err error
		action := runtime.CallFunctionOn("function() { return this; }").
			WithReturnByValue(true).
			WithAwaitPromise(true).
			WithObjectID(h.remoteObject.ObjectID)
		if remoteObject, _, err = action.Do(cdp.WithExecutor(h.ctx, h.session)); err != nil {
			return "", fmt.Errorf("retrieving json value: %w", err)
		}
	}

	res, err := parseConsoleRemoteObject(h.logger, remoteObject)
	if err != nil {
		return "", fmt.Errorf("extracting json value (remote object id: %v): %w", remoteObject.ObjectID, err)
	}

	return res, nil
}

// ObjectID returns the remote object ID.
func (h *BaseJSHandle) ObjectID() runtime.RemoteObjectID {
	return h.remoteObject.ObjectID
}

View on GitHub (pinned to 93accf6570)

Solutions

1. For DOM elements use element-specific accessors (textContent(), innerText(), getAttribute()) instead of jsonValue()
2. Serialize inside the page: page.evaluate('el => JSON.stringify(el.dataset)') and parse the string
3. If the handle comes from evaluateHandle, make the page function return plain JSON-able data (objects, arrays, primitives)
4. Inspect handleotype via handle.toString() / evaluation to confirm the value type before extraction

Example fix

// before
const h = await page.evaluateHandle('() => document.querySelector("#cfg")');
const json = await h.jsonValue();   // DOM node is not JSON-serializable

// after
const json = await page.evaluate('() => JSON.stringify(cfgObject)');
const cfg = JSON.parse(json);

// ensure the handle refers to JSON-able data, not a DOM node or function
const desc = await handle.toString();
if (/JSHandle@node|JSHandle@function|JSHandle@symbol/.test(desc)) {
  throw new Error('handle is not JSON-serializable; use page.evaluate instead');
}

try {
  return await handle.jsonValue();
} catch (e) {
  if (/extracting json value/.test(e.message)) {
    return JSON.parse(await page.evaluate('JSON.stringify(window.cfg)'));
  }
  throw e;
}

When it happens

Trigger: Calling jsonValue() on a handle to a DOM element (remote object is a node, not a plain value); on a function object; on a Symbol or undefined value; on an object whose description cannot be parsed by the console-object parser.

Common situations: Assuming jsonValue() works on element handles the way it does on value handles (e.g. from page.evaluateHandle returning a primitive wrapper); evaluating handle-returning expressions that yield functions or symbols.

Related errors

• retrieving json value: %w
• element is not attached to the DOM
• dispatching element event %q: %w
• selecting text: %w
• setting input files: %w

AI-assisted analysis of grafana/k6@93accf6570 (2026-08-15). Data as JSON: /api/errors/8bffc71eb2f290f4. Report an issue: GitHub.