improve code

packages/overlayscrollbars/src/environment.ts

@@ -16,6 +16,8 @@ import {
   getBoundingClientRect,
   assignDeep,
   cssProperty,
+  createCache,
+  equalXY,
 } from 'support';
 import {
   classNameEnvironment,
@@ -26,59 +28,72 @@ import {
 import { OSOptions, defaultOptions } from 'options';
 import { OSTargetElement, PartialOptions } from 'typings';
 
-type StructureInitializationElementFn<T> = ((target: OSTargetElement) => HTMLElement | T) | T;
+type StructureInitializationStrategyElementFn<T> =
+  | ((target: OSTargetElement) => HTMLElement | T)
+  | T;
 
-type ScrollbarsInitializationElementFn<T> =
+type ScrollbarsInitializationStrategyElementFn<T> =
   | ((target: OSTargetElement, host: HTMLElement, viewport: HTMLElement) => HTMLElement | T)
   | T;
 
 /**
  * A Static element is an element which MUST be generated.
- * If null (or the returned result is null), the initialization function is generatig the element, otherwise
+ * If null or undefined (or the returned result is null or undefined), the initialization function is generatig the element, otherwise
  * the element returned by the function acts as the generated element.
  */
-export type StructureInitializationStaticElement = StructureInitializationElementFn<null>;
+export type StructureInitializationStrategyStaticElement = StructureInitializationStrategyElementFn<
+  null | undefined
+>;
 
 /**
  * A Dynamic element is an element which CAN be generated.
- * If null (or the returned result is null), then the default behavior is used.
  * If boolean (or the returned result is boolean), the generation of the element is forced (or not).
  * If the function returns and element, the element returned by the function acts as the generated element.
  */
-export type StructureInitializationDynamicElement = StructureInitializationElementFn<
+export type StructureInitializationStrategyDynamicElement =
-  boolean | null
+  StructureInitializationStrategyElementFn<boolean>;
->;
 
 export interface StructureInitializationStrategy {
-  _host: StructureInitializationStaticElement;
+  _host: StructureInitializationStrategyStaticElement;
-  _viewport: StructureInitializationStaticElement;
+  _viewport: StructureInitializationStrategyStaticElement;
-  _padding: StructureInitializationDynamicElement;
+  _padding: StructureInitializationStrategyDynamicElement;
-  _content: StructureInitializationDynamicElement;
+  _content: StructureInitializationStrategyDynamicElement;
 }
 
 export interface ScrollbarsInitializationStrategy {
-  _scrollbarsSlot: ScrollbarsInitializationElementFn<null | undefined>;
+  /**
+   * The scrollbars slot.  If null or undefined (or the returned result is null or undefined), the initialization function is deciding the element, otherwise
+   * the element returned by the function acts as the scrollbars slot.
+   */
+  _scrollbarsSlot: ScrollbarsInitializationStrategyElementFn<null | undefined>;
 }
 
 export interface InitializationStrategy
   extends StructureInitializationStrategy,
     ScrollbarsInitializationStrategy {}
 
+export type DefaultInitializationStrategy = {
+  [K in keyof InitializationStrategy]: Extract<
+    InitializationStrategy[K],
+    boolean | null | undefined
+  >;
+};
+
 export type OnEnvironmentChanged = (env: Environment) => void;
 export interface Environment {
-  _nativeScrollbarSize: XY;
+  readonly _nativeScrollbarSize: XY;
-  _nativeScrollbarIsOverlaid: XY<boolean>;
+  readonly _nativeScrollbarIsOverlaid: XY<boolean>;
-  _nativeScrollbarStyling: boolean;
+  readonly _nativeScrollbarStyling: boolean;
-  _rtlScrollBehavior: { n: boolean; i: boolean };
+  readonly _rtlScrollBehavior: { n: boolean; i: boolean };
-  _flexboxGlue: boolean;
+  readonly _flexboxGlue: boolean;
-  _cssCustomProperties: boolean;
+  readonly _cssCustomProperties: boolean;
+  readonly _defaultInitializationStrategy: DefaultInitializationStrategy;
+  readonly _defaultDefaultOptions: OSOptions;
   _addListener(listener: OnEnvironmentChanged): () => void;
   _getInitializationStrategy(): InitializationStrategy;
   _setInitializationStrategy(newInitializationStrategy: Partial<InitializationStrategy>): void;
   _getDefaultOptions(): OSOptions;
   _setDefaultOptions(newDefaultOptions: PartialOptions<OSOptions>): void;
-  _defaultInitializationStrategy: InitializationStrategy;
-  _defaultDefaultOptions: OSOptions;
 }
 
 let environmentInstance: Environment;
@@ -168,14 +183,13 @@ const getWindowDPR = (): number => {
   return window.devicePixelRatio || dDPI / sDPI;
 };
 
-// init function decides for all values
 const getDefaultInitializationStrategy = (
   nativeScrollbarStyling: boolean
-): InitializationStrategy => ({
+): DefaultInitializationStrategy => ({
   _host: null,
   _viewport: null,
-  _padding: null,
+  _padding: !nativeScrollbarStyling,
-  _content: null,
+  _content: false,
   _scrollbarsSlot: null,
 });
 
@@ -185,15 +199,18 @@ const createEnvironment = (): Environment => {
   const envElm = envDOM[0] as HTMLElement;
   const envChildElm = envElm.firstChild as HTMLElement;
   const onChangedListener: Set<OnEnvironmentChanged> = new Set();
-  const nativeScrollbarSize = getNativeScrollbarSize(body, envElm);
+  const [updateNativeScrollbarSizeCache, getNativeScrollbarSizeCache] = createCache({
+    _initialValue: getNativeScrollbarSize(body, envElm),
+    _equal: equalXY,
+  });
+  const [nativeScrollbarSize] = getNativeScrollbarSizeCache();
   const nativeScrollbarStyling = getNativeScrollbarStyling(envElm);
   const nativeScrollbarIsOverlaid = {
     x: nativeScrollbarSize.x === 0,
     y: nativeScrollbarSize.y === 0,
   };
-  const defaultInitializationStrategy = getDefaultInitializationStrategy(nativeScrollbarStyling);
+  const initializationStrategy = getDefaultInitializationStrategy(nativeScrollbarStyling);
-  let initializationStrategy = defaultInitializationStrategy;
+  const defaultDefaultOptions = assignDeep({}, defaultOptions);
-  let defaultDefaultOptions = defaultOptions;
 
   const env: Environment = {
     _nativeScrollbarSize: nativeScrollbarSize,
@@ -206,16 +223,24 @@ const createEnvironment = (): Environment => {
       onChangedListener.add(listener);
       return () => onChangedListener.delete(listener);
     },
-    _getInitializationStrategy: () => ({ ...initializationStrategy }),
+    _getInitializationStrategy: assignDeep<InitializationStrategy, InitializationStrategy>.bind(
+      0,
+      {} as InitializationStrategy,
+      initializationStrategy
+    ),
     _setInitializationStrategy(newInitializationStrategy) {
-      initializationStrategy = assignDeep({}, initializationStrategy, newInitializationStrategy);
+      assignDeep(initializationStrategy, newInitializationStrategy);
     },
-    _getDefaultOptions: () => ({ ...defaultDefaultOptions }),
+    _getDefaultOptions: assignDeep<OSOptions, OSOptions>.bind(
+      0,
+      {} as OSOptions,
+      defaultDefaultOptions
+    ),
     _setDefaultOptions(newDefaultOptions) {
-      defaultDefaultOptions = assignDeep({}, defaultDefaultOptions, newDefaultOptions);
+      assignDeep(defaultDefaultOptions, newDefaultOptions);
     },
-    _defaultInitializationStrategy: defaultInitializationStrategy,
+    _defaultInitializationStrategy: assignDeep({}, initializationStrategy),
-    _defaultDefaultOptions: defaultDefaultOptions,
+    _defaultDefaultOptions: assignDeep({}, defaultDefaultOptions),
   };
 
   removeAttr(envElm, 'style');
@@ -224,7 +249,6 @@ const createEnvironment = (): Environment => {
   if (!nativeScrollbarStyling && (!nativeScrollbarIsOverlaid.x || !nativeScrollbarIsOverlaid.y)) {
     let size = windowSize();
     let dpr = getWindowDPR();
-    let scrollbarSize = nativeScrollbarSize;
 
     window.addEventListener('resize', () => {
       if (onChangedListener.size) {
@@ -251,18 +275,16 @@ const createEnvironment = (): Environment => {
         const isZoom = deltaIsBigger && difference && dprChanged;
 
         if (isZoom) {
-          const newScrollbarSize = getNativeScrollbarSize(body, envElm);
+          const [scrollbarSize, scrollbarSizeChanged] = updateNativeScrollbarSizeCache(
-          // keep the object same!
+            getNativeScrollbarSize(body, envElm)
-          environmentInstance._nativeScrollbarSize.x = newScrollbarSize.x;
+          );
-          environmentInstance._nativeScrollbarSize.y = newScrollbarSize.y;
 
+          assignDeep(environmentInstance._nativeScrollbarSize, scrollbarSize); // keep the object same!
           removeElements(envElm);
 
-          if (scrollbarSize.x !== newScrollbarSize.x || scrollbarSize.y !== newScrollbarSize.y) {
+          if (scrollbarSizeChanged) {
             runEach(onChangedListener);
           }
-
-          scrollbarSize = newScrollbarSize;
         }
 
         size = sizeNew;

packages/overlayscrollbars/src/options.ts

@@ -1,5 +1,5 @@
 import { assignDeep, each, isObject, keys, isArray, hasOwnProperty, isFunction } from 'support';
-import { PartialOptions } from 'typings';
+import { PartialOptions, ReadonlyOptions } from 'typings';
 
 const stringify = (value: any) =>
   JSON.stringify(value, (_, val) => {
@@ -83,6 +83,8 @@ export interface OSOptions {
   */
 }
 
+export type ReadonlyOSOptions = ReadonlyOptions<OSOptions>;
+
 export interface OverflowChangedArgs {
   x: boolean;
   y: boolean;

packages/overlayscrollbars/src/overlayscrollbars.ts

@@ -1,7 +1,7 @@
 import { OSTarget, OSInitializationObject, PartialOptions } from 'typings';
 import { assignDeep, isEmptyObject, each, isFunction, keys, isHTMLElement, WH, XY } from 'support';
 import { createStructureSetup, createScrollbarsSetup } from 'setups';
-import { getOptionsDiff, OSOptions } from 'options';
+import { getOptionsDiff, OSOptions, ReadonlyOSOptions } from 'options';
 import { getEnvironment } from 'environment';
 import {
   getPlugins,
@@ -78,7 +78,11 @@ export const OverlayScrollbars: OverlayScrollbarsStatic = (
     const validate = optionsValidationPlugin && optionsValidationPlugin._;
     return validate ? validate(opts, true) : opts;
   };
-  const currentOptions: OSOptions = assignDeep({}, _getDefaultOptions(), validateOptions(options));
+  const currentOptions: ReadonlyOSOptions = assignDeep(
+    {},
+    _getDefaultOptions(),
+    validateOptions(options)
+  );
   const [addEvent, removeEvent, triggerEvent] = createOSEventListenerHub(eventListeners);
 
   if (

packages/overlayscrollbars/src/setups/scrollbarsSetup/scrollbarsSetup.ts

@@ -4,7 +4,7 @@ import {
   ScrollbarsSetupElementsObj,
 } from 'setups/scrollbarsSetup/scrollbarsSetup.elements';
 import type { StructureSetupElementsObj } from 'setups/structureSetup/structureSetup.elements';
-import type { OSOptions } from 'options';
+import type { ReadonlyOSOptions } from 'options';
 import type { Setup } from 'setups';
 import type { OSTarget } from 'typings';
 
@@ -17,7 +17,7 @@ export interface ScrollbarsSetupStaticState {
 
 export const createScrollbarsSetup = (
   target: OSTarget,
-  options: OSOptions,
+  options: ReadonlyOSOptions,
   structureSetupElements: StructureSetupElementsObj
 ): Setup<ScrollbarsSetupState, ScrollbarsSetupStaticState> => {
   const state = createState({});

packages/overlayscrollbars/src/setups/setups.ts

@@ -1,5 +1,5 @@
 import { assignDeep, hasOwnProperty } from 'support';
-import type { OSOptions } from 'options';
+import type { OSOptions, ReadonlyOSOptions } from 'options';
 import type { PartialOptions } from 'typings';
 
 export type SetupElements<T extends Record<string, any>> = [elements: T, destroy: () => void];
@@ -35,7 +35,7 @@ const getPropByPath = <T>(obj: any, path: string): T =>
 
 export const createOptionCheck =
   (
-    options: OSOptions,
+    options: ReadonlyOSOptions,
     changedOptions: PartialOptions<OSOptions>,
     force?: boolean
   ): SetupUpdateCheckOption =>

packages/overlayscrollbars/src/setups/structureSetup/structureSetup.elements.ts

@@ -28,9 +28,8 @@ import {
 } from 'classnames';
 import {
   getEnvironment,
-  StructureInitializationStaticElement,
+  StructureInitializationStrategyStaticElement,
-  StructureInitializationDynamicElement,
+  StructureInitializationStrategyDynamicElement,
-  StructureInitializationStrategy,
 } from 'environment';
 import { OSTarget, OSTargetElement, StructureInitialization } from 'typings';
 
@@ -81,20 +80,20 @@ const createUniqueViewportArrangeElement = (): HTMLStyleElement | false => {
 const staticCreationFromStrategy = (
   target: OSTargetElement,
   initializationValue: HTMLElement | undefined,
-  strategy: StructureInitializationStaticElement,
+  strategy: StructureInitializationStrategyStaticElement,
   elementClass: string
 ): HTMLElement => {
   const result =
-    initializationValue || (isFunction(strategy) ? strategy(target) : (strategy as null));
+    initializationValue ||
+    (isFunction(strategy) ? strategy(target) : (strategy as null | undefined));
   return result || createDiv(elementClass);
 };
 
 const dynamicCreationFromStrategy = (
   target: OSTargetElement,
   initializationValue: HTMLElement | boolean | undefined,
-  strategy: StructureInitializationDynamicElement,
+  strategy: StructureInitializationStrategyDynamicElement,
-  elementClass: string,
+  elementClass: string
-  defaultValue: boolean
 ): HTMLElement | false => {
   const takeInitializationValue = isBoolean(initializationValue) || initializationValue;
   const result = takeInitializationValue
@@ -103,10 +102,6 @@ const dynamicCreationFromStrategy = (
     ? strategy(target)
     : strategy;
 
-  if (result === null) {
-    return defaultValue ? createDiv(elementClass) : false;
-  }
-
   return result === true ? createDiv(elementClass) : result;
 };
 
@@ -117,7 +112,7 @@ export const createStructureSetupElements = (target: OSTarget): StructureSetupEl
     _viewport: viewportInitializationStrategy,
     _padding: paddingInitializationStrategy,
     _content: contentInitializationStrategy,
-  } = _getInitializationStrategy() as StructureInitializationStrategy;
+  } = _getInitializationStrategy();
   const targetIsElm = isHTMLElement(target);
   const targetStructureInitialization = target as StructureInitialization;
   const targetElement = targetIsElm
@@ -125,7 +120,7 @@ export const createStructureSetupElements = (target: OSTarget): StructureSetupEl
     : targetStructureInitialization.target;
   const isTextarea = is(targetElement, 'textarea');
   const isBody = !isTextarea && is(targetElement, 'body');
-  const ownerDocument: HTMLDocument = targetElement!.ownerDocument;
+  const ownerDocument = targetElement!.ownerDocument;
   const bodyElm = ownerDocument.body as HTMLBodyElement;
   const wnd = ownerDocument.defaultView as Window;
   const evaluatedTargetObj: StructureSetupElementsObj = {
@@ -148,15 +143,13 @@ export const createStructureSetupElements = (target: OSTarget): StructureSetupEl
       targetElement,
       targetStructureInitialization.padding,
       paddingInitializationStrategy,
-      classNamePadding,
+      classNamePadding
-      !_nativeScrollbarStyling // default value for padding
     ),
     _content: dynamicCreationFromStrategy(
       targetElement,
       targetStructureInitialization.content,
       contentInitializationStrategy,
-      classNameContent,
+      classNameContent
-      false // default value for content
     ),
     _viewportArrange: createUniqueViewportArrangeElement(),
     _windowElm: wnd,

packages/overlayscrollbars/src/setups/structureSetup/structureSetup.ts

@@ -6,7 +6,7 @@ import { createStructureSetupObservers } from 'setups/structureSetup/structureSe
 import type { StructureSetupUpdateHints } from 'setups/structureSetup/structureSetup.update';
 import type { StructureSetupElementsObj } from 'setups/structureSetup/structureSetup.elements';
 import type { TRBL, CacheValues, XY, WH } from 'support';
-import type { OSOptions } from 'options';
+import type { OSOptions, ReadonlyOSOptions } from 'options';
 import type { Setup } from 'setups';
 import type { OSTarget, PartialOptions, StyleObject } from 'typings';
 
@@ -64,7 +64,7 @@ const initialStructureSetupUpdateState: StructureSetupState = {
 
 export const createStructureSetup = (
   target: OSTarget,
-  options: OSOptions
+  options: ReadonlyOSOptions
 ): Setup<StructureSetupState, StructureSetupStaticState> => {
   const checkOptionsFallback = createOptionCheck(options, {});
   const state = createState(initialStructureSetupUpdateState);

packages/overlayscrollbars/src/typings.ts

@@ -2,6 +2,10 @@ export type PartialOptions<T> = {
   [P in keyof T]?: T[P] extends Record<string, unknown> ? PartialOptions<T[P]> : T[P];
 };
 
+export type ReadonlyOptions<T> = {
+  readonly [P in keyof T]: T[P] extends Record<string, unknown> ? ReadonlyOptions<T[P]> : T[P];
+};
+
 export type PlainObject<T = any> = { [name: string]: T };
 
 export type StyleObject<CustomCssProps = ''> = {

packages/overlayscrollbars/tests/jest/setups/structureSetup/structureSetup.elements.test.ts

@@ -1,7 +1,7 @@
 import {
   Environment,
-  StructureInitializationStaticElement,
+  StructureInitializationStrategyStaticElement,
-  StructureInitializationDynamicElement,
+  StructureInitializationStrategyDynamicElement,
 } from 'environment';
 import { OSTarget, StructureInitialization } from 'typings';
 import {
@@ -167,8 +167,9 @@ const assertCorrectSetupElements = (
     elm: Element | null,
     input: HTMLElement | boolean | undefined,
     isStaticStrategy: boolean,
-    strategy: StructureInitializationStaticElement | StructureInitializationDynamicElement,
+    strategy:
-    id: string
+      | StructureInitializationStrategyStaticElement
+      | StructureInitializationStrategyDynamicElement
   ) => {
     if (input) {
       expect(elm).toBeTruthy();
@@ -178,7 +179,7 @@ const assertCorrectSetupElements = (
       }
       if (input === undefined) {
         if (isStaticStrategy) {
-          strategy = strategy as StructureInitializationStaticElement;
+          strategy = strategy as StructureInitializationStrategyStaticElement;
           if (typeof strategy === 'function') {
             const result = strategy(target);
             if (result) {
@@ -190,21 +191,14 @@ const assertCorrectSetupElements = (
             expect(elm).toBeTruthy();
           }
         } else {
-          strategy = strategy as StructureInitializationDynamicElement;
+          strategy = strategy as StructureInitializationStrategyDynamicElement;
-          const expectDefaultValue = () => {
+          expect(strategy).not.toBe(null);
-            if (id === 'padding') {
+          expect(strategy).not.toBe(undefined);
-              if (_nativeScrollbarStyling) {
-                expect(elm).toBeFalsy();
-              } else {
-                expect(elm).toBeTruthy();
-              }
-            } else if (id === 'content') {
-              expect(elm).toBeFalsy();
-            }
-          };
           if (typeof strategy === 'function') {
             const result = strategy(target);
             const resultIsBoolean = typeof result === 'boolean';
+            expect(result).not.toBe(null);
+            expect(result).not.toBe(undefined);
             if (resultIsBoolean) {
               if (result) {
                 expect(elm).toBeTruthy();
@@ -213,8 +207,6 @@ const assertCorrectSetupElements = (
               }
             } else if (result) {
               expect(elm).toBe(result);
-            } else {
-              expectDefaultValue();
             }
           } else {
             const strategyIsBoolean = typeof strategy === 'boolean';
@@ -224,8 +216,6 @@ const assertCorrectSetupElements = (
               } else {
                 expect(elm).toBeFalsy();
               }
-            } else {
-              expectDefaultValue();
             }
           }
         }
@@ -240,10 +230,10 @@ const assertCorrectSetupElements = (
   }
 
   if (inputIsElement) {
-    checkStrategyDependendElements(padding, undefined, false, paddingInitStrategy, 'padding');
+    checkStrategyDependendElements(padding, undefined, false, paddingInitStrategy);
-    checkStrategyDependendElements(content, undefined, false, contentInitStrategy, 'content');
+    checkStrategyDependendElements(content, undefined, false, contentInitStrategy);
-    checkStrategyDependendElements(viewport, undefined, true, viewportInitStrategy, 'viewport');
+    checkStrategyDependendElements(viewport, undefined, true, viewportInitStrategy);
-    checkStrategyDependendElements(host, undefined, true, hostInitStrategy, 'host');
+    checkStrategyDependendElements(host, undefined, true, hostInitStrategy);
   } else {
     const {
       padding: inputPadding,
@@ -251,10 +241,10 @@ const assertCorrectSetupElements = (
       viewport: inputViewport,
       host: inputHost,
     } = inputAsObj;
-    checkStrategyDependendElements(padding, inputPadding, false, paddingInitStrategy, 'padding');
+    checkStrategyDependendElements(padding, inputPadding, false, paddingInitStrategy);
-    checkStrategyDependendElements(content, inputContent, false, contentInitStrategy, 'content');
+    checkStrategyDependendElements(content, inputContent, false, contentInitStrategy);
-    checkStrategyDependendElements(viewport, inputViewport, true, viewportInitStrategy, 'viewport');
+    checkStrategyDependendElements(viewport, inputViewport, true, viewportInitStrategy);
-    checkStrategyDependendElements(host, inputHost, true, hostInitStrategy, 'host');
+    checkStrategyDependendElements(host, inputHost, true, hostInitStrategy);
   }
 
   return [elements, destroy];
@@ -327,8 +317,12 @@ const envInitStrategyAssigned = {
     _getInitializationStrategy: () => ({
       _host: () => document.querySelector('#host1') as HTMLElement,
       _viewport: (target: HTMLElement) => target.querySelector('#viewport') as HTMLElement,
-      _content: (target: HTMLElement) => target.querySelector('#content') as HTMLElement,
+      _content: (target: HTMLElement) =>
-      _padding: (target: HTMLElement) => target.querySelector('#padding') as HTMLElement,
+        target.querySelector<HTMLElement>('#content') ||
+        env._defaultInitializationStrategy._content,
+      _padding: (target: HTMLElement) =>
+        target.querySelector<HTMLElement>('#padding') ||
+        env._defaultInitializationStrategy._padding,
       _scrollbarsSlot: null,
     }),
   },