grafana/k6 · error

options: expected object, got %T

Error message

options: expected object, got %T

What it means

Thrown by ConvertSelectOptionValues when the selectOption argument classifies as an object/map (reflect.Map) but Sobek cannot export it to map[string]any (browser/mapping.go:89). The single-object form selectOption({value:'x'}) is valid, so this error means the map itself could not be read — typically a non-plain-object map-like value with non-string keys or an object from outside plain JS.

Solutions

1. Use a plain object literal: page.selectOption('#sel', { value: 'blue' }).
2. Convert Map instances first: Object.fromEntries(myMap).
3. Keep keys to 'value', 'label', 'index' with correct value types (string, string, int).
4. Verify with typeof obj === 'object' && !Array.isArray(obj) before the call.

Example fix

// before
await page.selectOption('#sel', new Map([['value', 'blue']]));

// after
await page.selectOption('#sel', { value: 'blue' });

const obj = raw instanceof Map ? Object.fromEntries(raw) : raw;
await page.selectOption('#sel', typeof obj === 'object' && obj !== null ? obj : { value: String(raw) });

function isPlainSelectObject(v) {
  return v != null && typeof v === 'object' && !Array.isArray(v) && !(v instanceof Map) && !(v instanceof Set);
}

try { await page.selectOption('#sel', obj); } catch (e) { if (/options: expected object/.test(e.message)) { await page.selectOption('#sel', Object.fromEntries(obj)); } else throw e; }

When it happens

Trigger: Passing a Map instance with non-string keys, or an object produced by a Go binding whose export type is a map with non-string key types, to page.selectOption('#sel', obj). Plain JS object literals with string keys never trigger this.

Common situations: Using new Map([['value','x']]) instead of an object literal; receiving option descriptors from exported Go functions; almost never occurs with hand-written objects in a test script.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

• options: expected array, got %T
• options: expected string or object, got %T
• options: unsupported type %T
• options[ ]: expected int, got %T
• options[ ]: expected string, got %T

AI-assisted analysis of grafana/k6@8d06114777 (2026-08-18). Data as JSON: /api/errors/c70c1b7059000f55. Report an issue: GitHub.

Appendix: source

Thrown at internal/js/modules/k6/browser/browser/mapping.go:97

				*valOpt.Value = item
				labelOpt := common.SelectOption{Label: new(string)}
				*labelOpt.Label = item
				opts = append(opts, &valOpt, &labelOpt)
			case map[string]any:
				opt, err := extractSelectOptionFromMap(item)
				if err != nil {
					return nil, err
				}

				opts = append(opts, opt)
			default:
				return nil, fmt.Errorf("options: expected string or object, got %T", item)
			}
		}
	case reflect.Map:
		var raw map[string]any
		if err := rt.ExportTo(values, &raw); err != nil {
			return nil, fmt.Errorf("options: expected object, got %T", values)
		}

		opt, err := extractSelectOptionFromMap(raw)
		if err != nil {
			return nil, err
		}

		opts = append(opts, opt)
	case reflect.TypeFor[*common.ElementHandle]().Kind():
		opts = append(opts, t.(*common.ElementHandle)) //nolint:forcetypeassert
	case reflect.TypeFor[sobek.Object]().Kind():
		obj := values.ToObject(rt)
		opt := common.SelectOption{}
		for _, k := range obj.Keys() {
			switch k {
			case "value":
				opt.Value = new(string)
				*opt.Value = obj.Get(k).String()

View on GitHub (pinned to 8d06114777)