grafana/k6 · error

no exported functions in script

Error message

no exported functions in script

What it means

After the export scan, the bundle found zero callable exports (b.callableExports is empty). k6 executes at least one exported function per iteration — normally the default function — so a script with no exported functions has nothing to run.

Source

Thrown at internal/js/bundle.go:238

					b.preInitState.Logger.WithError(err).Warn("There were unknown fields in the options exported in the script")
					err = nil
				}
			case consts.SetupFn:
				err = errors.New("exported 'setup' must be a function")
				return
			case consts.TeardownFn:
				err = errors.New("exported 'teardown' must be a function")
				return
			}
		}
	})
	<-ch
	if err != nil {
		return err
	}

	if len(b.callableExports) == 0 {
		return errors.New("no exported functions in script")
	}

	return nil
}

func beautifyOptionsJSONUnmarshalError(data []byte, err error) error {
	unmarshalTypError := new(json.UnmarshalTypeError)
	if errors.As(err, &unmarshalTypError) {
		e := unmarshalTypError
		previousNewLineIndex := max(bytes.LastIndexByte(data[:e.Offset], '\n'), 0)
		nextNewLineIndex := max(min(bytes.IndexByte(data[e.Offset:], '\n'), len(data)-1), (int)(e.Offset))

		info := strings.TrimSpace(string(data[previousNewLineIndex:nextNewLineIndex]))
		err = fmt.Errorf("parsing options from script got error while parsing %q: %w", info, e)
	}
	return err
}

View on GitHub (pinned to 93accf6570)

Solutions

1. Add a default function: `export default function () { /* test logic */ }`
2. If the file is really a helper module, point `k6 run` at the actual entry script instead
3. For scenarios-only configs, still export an (empty) default function so iterations exist

Example fix

// before
export const options = { vus: 1, duration: '10s' };

// after
export const options = { vus: 1, duration: '10s' };
export default function () { http.get('https://test.k6.io'); }

// entry-script guard: fail loudly if nothing is runnable
let hasDefault = false;
try { hasDefault = typeof module_default === 'function'; } catch (_) {}
// simpler: ensure the file literally contains 'export default function' before shipping
curl -s script.js | grep -q 'export default function' || echo 'WARN: no default export' >&2

When it happens

Trigger: A script exporting only `options` (or other constants) with no `export default function`; helper/util modules mistakenly passed to `k6 run` as the entry script.

Common situations: Options-only snippets saved as a script; refactors that wrapped the default function in a const without exporting it; running a shared library file directly.

Related errors

• exported 'setup' must be a function
• exported 'teardown' must be a function
• open() can't be used with an empty filename
• predicate function is not callable
• only arrays can be made into SharedArray

AI-assisted analysis of grafana/k6@93accf6570 (2026-08-15). Data as JSON: /api/errors/68ca62cb445740cd. Report an issue: GitHub.