Addon-knobs: fix knobs function return types

addons/knobs/src/KnobManager.ts

@@ -6,7 +6,8 @@ import { getQueryParams } from '@storybook/client-api';
 // eslint-disable-next-line import/no-extraneous-dependencies
 import { Channel } from '@storybook/channels';
 
-import KnobStore, { Knob } from './KnobStore';
+import KnobStore, { KnobStoreKnob } from './KnobStore';
+import { Knob, KnobType } from './type-defs';
 import { SET } from './shared';
 
 import { deserializers } from './converters';
@@ -71,7 +72,7 @@ export default class KnobManager {
     return this.options.escapeHTML ? escapeStrings(value) : value;
   }
 
-  knob(name: string, options: Knob) {
+  knob<T extends KnobType = any>(name: string, options: Knob<T>): Knob<T>['value'] {
     this._mayCallChannel();
 
     const knobName = options.groupId ? `${name}_${options.groupId}` : name;
@@ -93,7 +94,7 @@ export default class KnobManager {
       return this.getKnobValue(existingKnob);
     }
 
-    const knobInfo: Knob & { name: string; label: string; defaultValue?: any } = {
+    const knobInfo: Knob<T> & { name: string; label: string; defaultValue?: any } = {
       ...options,
       name: knobName,
       label: name,
@@ -110,7 +111,7 @@ export default class KnobManager {
       knobInfo.defaultValue = options.value;
     }
 
-    knobStore.set(knobName, knobInfo);
+    knobStore.set(knobName, knobInfo as KnobStoreKnob);
     return this.getKnobValue(knobStore.get(knobName));
   }
 

addons/knobs/src/KnobStore.ts

@@ -1,36 +1,7 @@
-import Types, {
-  TextTypeKnob,
-  NumberTypeKnob,
-  ColorTypeKnob,
-  BooleanTypeKnob,
-  ObjectTypeKnob,
-  SelectTypeKnob,
-  RadiosTypeKnob,
-  ArrayTypeKnob,
-  DateTypeKnob,
-  ButtonTypeOnClickProp,
-  FileTypeKnob,
-  OptionsTypeKnob,
-} from './components/types';
+import { Knob } from './type-defs';
 
 type Callback = () => any;
 
-type KnobPlus<T extends keyof typeof Types, K> = K & { type: T; groupId?: string };
-
-export type Knob =
-  | KnobPlus<'text', Pick<TextTypeKnob, 'value'>>
-  | KnobPlus<'boolean', Pick<BooleanTypeKnob, 'value'>>
-  | KnobPlus<'number', Pick<NumberTypeKnob, 'value' | 'range' | 'min' | 'max' | 'step'>>
-  | KnobPlus<'color', Pick<ColorTypeKnob, 'value'>>
-  | KnobPlus<'object', Pick<ObjectTypeKnob<any>, 'value'>>
-  | KnobPlus<'select', Pick<SelectTypeKnob, 'value' | 'options'> & { selectV2: true }>
-  | KnobPlus<'radios', Pick<RadiosTypeKnob, 'value' | 'options'>>
-  | KnobPlus<'array', Pick<ArrayTypeKnob, 'value' | 'separator'>>
-  | KnobPlus<'date', Pick<DateTypeKnob, 'value'>>
-  | KnobPlus<'files', Pick<FileTypeKnob, 'value' | 'accept'>>
-  | KnobPlus<'button', { value?: unknown; callback: ButtonTypeOnClickProp; hideLabel: true }>
-  | KnobPlus<'options', Pick<OptionsTypeKnob<any>, 'options' | 'value' | 'optionsObj'>>;
-
 export type KnobStoreKnob = Knob & {
   name: string;
   label: string;

addons/knobs/src/components/Panel.tsx

@@ -1,4 +1,4 @@
-import React, { PureComponent, Fragment, ComponentType } from 'react';
+import React, { PureComponent, Fragment } from 'react';
 import PropTypes from 'prop-types';
 import qs from 'qs';
 import { document } from 'global';
@@ -16,7 +16,7 @@ import {
 } from '@storybook/components';
 import { RESET, SET, CHANGE, SET_OPTIONS, CLICK } from '../shared';
 
-import Types from './types';
+import { getKnobControl } from './types';
 import PropForm from './PropForm';
 import { KnobStoreKnob } from '../KnobStore';
 
@@ -58,11 +58,6 @@ interface KnobPanelOptions {
   timestamps?: boolean;
 }
 
-type KnobControlType = ComponentType<any> & {
-  serialize: (v: any) => any;
-  deserialize: (v: any) => any;
-};
-
 export default class KnobPanel extends PureComponent<KnobPanelProps> {
   static propTypes = {
     active: PropTypes.bool.isRequired,
@@ -133,9 +128,9 @@ export default class KnobPanel extends PureComponent<KnobPanelProps> {
 
           // If the knob value present in url
           if (urlValue !== undefined) {
-            const value = (Types[knob.type] as KnobControlType).deserialize(urlValue);
+            const value = getKnobControl(knob.type).deserialize(urlValue);
             knob.value = value;
-            queryParams[`knob-${name}`] = (Types[knob.type] as KnobControlType).serialize(value);
+            queryParams[`knob-${name}`] = getKnobControl(knob.type).serialize(value);
 
             api.emit(CHANGE, knob);
           }
@@ -161,7 +156,7 @@ export default class KnobPanel extends PureComponent<KnobPanelProps> {
     const { knobs } = this.state;
 
     Object.entries(knobs).forEach(([name, knob]) => {
-      query[`knob-${name}`] = (Types[knob.type] as KnobControlType).serialize(knob.value);
+      query[`knob-${name}`] = getKnobControl(knob.type).serialize(knob.value);
     });
 
     copy(`${location.origin + location.pathname}?${qs.stringify(query, { encode: false })}`);
@@ -193,7 +188,7 @@ export default class KnobPanel extends PureComponent<KnobPanelProps> {
 
       Object.keys(newKnobs).forEach(n => {
         const knob = newKnobs[n];
-        queryParams[`knob-${n}`] = (Types[knob.type] as KnobControlType).serialize(knob.value);
+        queryParams[`knob-${n}`] = getKnobControl(knob.type).serialize(knob.value);
       });
 
       api.setQueryParams(queryParams);

addons/knobs/src/components/PropForm.tsx

@@ -2,7 +2,7 @@ import React, { Component, WeakValidationMap, ComponentType, Requireable } from
 import PropTypes from 'prop-types';
 
 import { Form } from '@storybook/components';
-import TypeMap from './types';
+import { getKnobControl } from './types';
 import { KnobStoreKnob } from '../KnobStore';
 
 interface PropFormProps {
@@ -48,7 +48,7 @@ export default class PropForm extends Component<PropFormProps> {
       <Form>
         {knobs.map(knob => {
           const changeHandler = this.makeChangeHandler(knob.name, knob.type);
-          const InputType: ComponentType<any> = TypeMap[knob.type] || InvalidType;
+          const InputType: ComponentType<any> = getKnobControl(knob.type) || InvalidType;
 
           return (
             <Form.Field key={knob.name} label={!knob.hideLabel && `${knob.label || knob.name}`}>

addons/knobs/src/components/types/index.ts

@@ -1,3 +1,5 @@
+import { ComponentType } from 'react';
+
 import TextType from './Text';
 import NumberType from './Number';
 import ColorType from './Color';
@@ -11,7 +13,7 @@ import ButtonType from './Button';
 import FilesType from './Files';
 import OptionsType from './Options';
 
-export default {
+const KnobControls = {
   text: TextType,
   number: NumberType,
   color: ColorType,
@@ -25,6 +27,17 @@ export default {
   files: FilesType,
   options: OptionsType,
 };
+export default KnobControls;
+
+export type KnobType = keyof typeof KnobControls;
+
+export type KnobControlType = ComponentType<any> & {
+  serialize: (v: any) => any;
+  deserialize: (v: any) => any;
+};
+
+// Note: this is a utility function that helps in resolving types more orderly
+export const getKnobControl = (type: KnobType): KnobControlType => KnobControls[type];
 
 export { TextTypeKnob } from './Text';
 export { NumberTypeKnob, NumberTypeKnobOptions } from './Number';

addons/knobs/src/index.ts

@@ -2,6 +2,7 @@ import addons, { makeDecorator } from '@storybook/addons';
 
 import { SET_OPTIONS } from './shared';
 import { manager, registerKnobs } from './registerKnobs';
+import { Knob, KnobType } from './type-defs';
 import {
   NumberTypeKnobOptions,
   ButtonTypeOnClickProp,
@@ -12,8 +13,8 @@ import {
   OptionsKnobOptions,
 } from './components/types';
 
-export function knob(name: string, optionsParam: any) {
-  return manager.knob(name, optionsParam);
+export function knob<T extends KnobType>(name: string, options: Knob<T>) {
+  return manager.knob(name, options);
 }
 
 export function text(name: string, value: string, groupId?: string) {
@@ -57,7 +58,7 @@ export function color(name: string, value: string, groupId?: string) {
   return manager.knob(name, { type: 'color', value, groupId });
 }
 
-export function object<T>(name: string, value: T, groupId?: string) {
+export function object<T>(name: string, value: T, groupId?: string): T {
   return manager.knob(name, { type: 'object', value, groupId });
 }
 
@@ -99,10 +100,10 @@ export function files(name: string, accept: string, value: string[] = [], groupI
 export function optionsKnob<T>(
   name: string,
   valuesObj: OptionsTypeOptionsProp<T>,
-  value: string,
+  value: T,
   optionsObj: OptionsKnobOptions,
   groupId?: string
-) {
+): T {
   return manager.knob(name, { type: 'options', options: valuesObj, value, optionsObj, groupId });
 }
 

addons/knobs/src/type-defs.ts

@@ -0,0 +1,45 @@
+import {
+  TextTypeKnob,
+  NumberTypeKnob,
+  ColorTypeKnob,
+  BooleanTypeKnob,
+  ObjectTypeKnob,
+  SelectTypeKnob,
+  RadiosTypeKnob,
+  ArrayTypeKnob,
+  DateTypeKnob,
+  ButtonTypeOnClickProp,
+  FileTypeKnob,
+  OptionsTypeKnob,
+  KnobType,
+} from './components/types';
+
+type KnobPlus<T extends KnobType, K> = K & { type: T; groupId?: string };
+
+export type Knob<T extends KnobType = any> = T extends 'text'
+  ? KnobPlus<T, Pick<TextTypeKnob, 'value'>>
+  : T extends 'boolean'
+  ? KnobPlus<T, Pick<BooleanTypeKnob, 'value'>>
+  : T extends 'number'
+  ? KnobPlus<T, Pick<NumberTypeKnob, 'value' | 'range' | 'min' | 'max' | 'step'>>
+  : T extends 'color'
+  ? KnobPlus<T, Pick<ColorTypeKnob, 'value'>>
+  : T extends 'object'
+  ? KnobPlus<T, Pick<ObjectTypeKnob<any>, 'value'>>
+  : T extends 'select'
+  ? KnobPlus<T, Pick<SelectTypeKnob, 'value' | 'options'> & { selectV2: true }>
+  : T extends 'radios'
+  ? KnobPlus<T, Pick<RadiosTypeKnob, 'value' | 'options'>>
+  : T extends 'array'
+  ? KnobPlus<T, Pick<ArrayTypeKnob, 'value' | 'separator'>>
+  : T extends 'date'
+  ? KnobPlus<T, Pick<DateTypeKnob, 'value'>>
+  : T extends 'files'
+  ? KnobPlus<T, Pick<FileTypeKnob, 'value' | 'accept'>>
+  : T extends 'button'
+  ? KnobPlus<T, { value?: never; callback: ButtonTypeOnClickProp; hideLabel: true }>
+  : T extends 'options'
+  ? KnobPlus<T, Pick<OptionsTypeKnob<any>, 'options' | 'value' | 'optionsObj'>>
+  : never;
+
+export { KnobType };