grafana/k6 · error

missing required argument 'label'

Error message

missing required argument 'label'

What it means

Thrown by the Page mapping's getByLabel method. The label text is the mandatory first argument; the mapping checks it with k6common.IsNullish before calling p.GetByLabel with parsed base options (string or RegExp plus exact/substring options). Nullish input is rejected up front.

Source

Thrown at internal/js/modules/k6/browser/browser/page_mapping.go:191

				return nil, errors.New("missing required argument 'role'")
			}
			popts := parseGetByRoleOptions(vu.Context(), opts)

			ml := mapLocator(vu, p.GetByRole(role.String(), popts))
			return rt.ToValue(ml).ToObject(rt), nil
		},
		"getByAltText": func(alt sobek.Value, opts sobek.Value) (*sobek.Object, error) {
			if k6common.IsNullish(alt) {
				return nil, errors.New("missing required argument 'altText'")
			}
			palt, popts := parseGetByBaseOptions(vu.Context(), alt, false, opts)

			ml := mapLocator(vu, p.GetByAltText(palt, popts))
			return rt.ToValue(ml).ToObject(rt), nil
		},
		"getByLabel": func(label sobek.Value, opts sobek.Value) (*sobek.Object, error) {
			if k6common.IsNullish(label) {
				return nil, errors.New("missing required argument 'label'")
			}
			plabel, popts := parseGetByBaseOptions(vu.Context(), label, true, opts)

			ml := mapLocator(vu, p.GetByLabel(plabel, popts))
			return rt.ToValue(ml).ToObject(rt), nil
		},
		"getByPlaceholder": func(placeholder sobek.Value, opts sobek.Value) (*sobek.Object, error) {
			if k6common.IsNullish(placeholder) {
				return nil, errors.New("missing required argument 'placeholder'")
			}
			pplaceholder, popts := parseGetByBaseOptions(vu.Context(), placeholder, false, opts)

			ml := mapLocator(vu, p.GetByPlaceholder(pplaceholder, popts))
			return rt.ToValue(ml).ToObject(rt), nil
		},
		"getByTitle": func(title sobek.Value, opts sobek.Value) (*sobek.Object, error) {
			if k6common.IsNullish(title) {
				return nil, errors.New("missing required argument 'title'")

View on GitHub (pinned to 93accf6570)

Solutions

1. Pass a string or RegExp: page.getByLabel('Email') or page.getByLabel(/email/i)
2. Guard data-driven labels: page.getByLabel(label ?? 'Email')
3. Add a quick assertion on the data source so missing labels fail with your own message

Example fix

// before
page.getByLabel();

// after
page.getByLabel('Email');

if (label === undefined || label === null) {
  throw new Error(`page.getByLabel: 'label' is required, got ${label}`);
}
const loc = page.getByLabel(label, opts);

function isTextMatcher(v) {
  return typeof v === 'string' || v instanceof RegExp;
}

try {
  page.getByLabel(label);
} catch (e) {
  if (!e.message.includes("missing required argument 'label'")) throw e;
  throw new Error(`form label missing from data file`);
}

When it happens

Trigger: page.getByLabel() with no arguments; page.getByLabel(null); label variables that resolve to undefined (missing form definitions in fixtures).

Common situations: Form-testing scripts where the label comes from a data file with gaps; converting page.$('label:has-text(...)') selectors to getByLabel without carrying the text over; optional chaining upstream that silently yields undefined.

Related errors

• missing required argument 'role'
• missing required argument 'altText'
• missing required argument 'placeholder'
• missing required argument 'title'
• missing required argument 'testId'

AI-assisted analysis of grafana/k6@93accf6570 (2026-08-15). Data as JSON: /api/errors/3fcb9799a8ebf82f. Report an issue: GitHub.