grafana/k6 · error

evaluate requires a page function

Error message

evaluate requires a page function

What it means

Error "evaluate requires a page function" thrown in grafana/k6.

Source

Thrown at internal/js/modules/k6/browser/browser/page_mapping.go:107

			}), nil
		},
		"emulateMedia": func(opts sobek.Value) (*sobek.Promise, error) {
			popts, err := parsePageEmulateMediaOptions(rt, opts, common.NewPageEmulateMediaOptions(p))
			if err != nil {
				return nil, fmt.Errorf("parsing emulateMedia options: %w", err)
			}
			return promise(vu, func() (any, error) {
				return nil, p.EmulateMedia(popts) //nolint:wrapcheck
			}), nil
		},
		"emulateVisionDeficiency": func(typ string) *sobek.Promise {
			return promise(vu, func() (any, error) {
				return nil, p.EmulateVisionDeficiency(typ) //nolint:wrapcheck
			})
		},
		"evaluate": func(pageFunc sobek.Value, gargs ...sobek.Value) (*sobek.Promise, error) {
			if sobekEmptyString(pageFunc) {
				return nil, fmt.Errorf("evaluate requires a page function")
			}
			funcString := pageFunc.String()
			gopts := exportArgs(gargs)
			return promise(vu, func() (any, error) {
				return p.Evaluate(funcString, gopts...)
			}), nil
		},
		"evaluateHandle": func(pageFunc sobek.Value, gargs ...sobek.Value) (*sobek.Promise, error) {
			if sobekEmptyString(pageFunc) {
				return nil, fmt.Errorf("evaluateHandle requires a page function")
			}
			funcString := pageFunc.String()
			gopts := exportArgs(gargs)
			return promise(vu, func() (any, error) {
				jsh, err := p.EvaluateHandle(funcString, gopts...)
				if err != nil {
					return nil, err //nolint:wrapcheck
				}

View on GitHub (pinned to 93accf6570)

When it happens

Trigger: Thrown at internal/js/modules/k6/browser/browser/page_mapping.go:107 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of grafana/k6@93accf6570 (2026-08-15). Data as JSON: /api/errors/44ef49d48fe93b94. Report an issue: GitHub.