improve react initialization and api

packages/overlayscrollbars-react/src/OverlayScrollbarsComponent.tsx

@@ -11,24 +11,36 @@ export type OverlayScrollbarsComponentProps<T extends keyof JSX.IntrinsicElement
   };
 
 export interface OverlayScrollbarsComponentRef<T extends keyof JSX.IntrinsicElements = 'div'> {
-  osInstance(): OverlayScrollbars | null;
+  instance(): OverlayScrollbars | null;
-  osTarget(): ElementRef<T> | null;
+  target(): ElementRef<T> | null;
 }
 
 const OverlayScrollbarsComponent = <T extends keyof JSX.IntrinsicElements>(
   props: OverlayScrollbarsComponentProps<T>,
   ref: ForwardedRef<OverlayScrollbarsComponentRef<T>>
 ) => {
-  const { element = 'div', options, events, ...other } = props;
+  const { element = 'div', options, events, children, ...other } = props;
   const Tag = element;
 
   const osTargetRef = useRef<ElementRef<T>>(null);
+  const osChildrenRef = useRef<HTMLDivElement>(null);
   const osInstanceRef = useRef<OverlayScrollbars | null>(null);
 
   useEffect(() => {
-    const { current: target } = osTargetRef;
+    const { current: targetElm } = osTargetRef;
-    if (target) {
+    const { current: childrenElm } = osChildrenRef;
-      const instance = OverlayScrollbars(target as any, options || {}, events);
+    if (targetElm && childrenElm) {
+      const instance = OverlayScrollbars(
+        {
+          target: targetElm as any,
+          elements: {
+            viewport: childrenElm,
+            content: childrenElm,
+          },
+        },
+        options || {},
+        events
+      );
       osInstanceRef.current = instance;
 
       return () => instance.destroy();
@@ -53,15 +65,19 @@ const OverlayScrollbarsComponent = <T extends keyof JSX.IntrinsicElements>(
     ref,
     () => {
       return {
-        osInstance: () => osInstanceRef.current,
+        instance: () => osInstanceRef.current,
-        osTarget: () => osTargetRef.current,
+        target: () => osTargetRef.current,
       };
     },
     []
   );
 
+  return (
     // @ts-ignore
-  return <Tag data-overlayscrollbars="" {...other} ref={osTargetRef} />;
+    <Tag data-overlayscrollbars="" {...other} ref={osTargetRef}>
+      <div ref={osChildrenRef}>{children}</div>
+    </Tag>
+  );
 };
 
 const OverlayScrollbarsComponentForwardedRef = forwardRef(OverlayScrollbarsComponent) as <

packages/overlayscrollbars-react/test/OverlayScrollbarsComponent.test.tsx

@@ -61,11 +61,11 @@ describe('OverlayScrollbarsComponent', () => {
     const ref: RefObject<OverlayScrollbarsComponentRef> = { current: null };
     const { container } = render(<OverlayScrollbarsComponent ref={ref} />);
 
-    const { osInstance, osTarget } = ref.current!;
+    const { instance, target } = ref.current!;
-    expect(osInstance).toBeTypeOf('function');
+    expect(instance).toBeTypeOf('function');
-    expect(osTarget).toBeTypeOf('function');
+    expect(target).toBeTypeOf('function');
-    expect(OverlayScrollbars.valid(osInstance())).toBe(true);
+    expect(OverlayScrollbars.valid(instance())).toBe(true);
-    expect(osTarget()).toBe(container.firstElementChild);
+    expect(target()).toBe(container.firstElementChild);
   });
 
   test('options', () => {
@@ -77,13 +77,13 @@ describe('OverlayScrollbarsComponent', () => {
       />
     );
 
-    const opts = ref.current!.osInstance()!.options();
+    const opts = ref.current!.instance()!.options();
     expect(opts.paddingAbsolute).toBe(true);
     expect(opts.overflow.y).toBe('hidden');
 
     rerender(<OverlayScrollbarsComponent options={{ overflow: { x: 'hidden' } }} ref={ref} />);
 
-    const newOpts = ref.current!.osInstance()!.options()!;
+    const newOpts = ref.current!.instance()!.options()!;
     expect(newOpts.paddingAbsolute).toBe(false); //switches back to default because its not specified in the new options
     expect(newOpts.overflow.y).toBe('scroll'); //switches back to default because its not specified in the new options
     expect(newOpts.overflow.x).toBe('hidden');
@@ -103,7 +103,7 @@ describe('OverlayScrollbarsComponent', () => {
 
     expect(onUpdated).not.toHaveBeenCalled();
 
-    ref.current?.osInstance()?.update(true);
+    ref.current!.instance()!.update(true);
     expect(onUpdatedInitial).toHaveBeenCalledTimes(1);
     expect(onUpdated).toHaveBeenCalledTimes(1);
 
@@ -111,14 +111,14 @@ describe('OverlayScrollbarsComponent', () => {
       <OverlayScrollbarsComponent events={{ updated: [onUpdated, onUpdatedInitial] }} ref={ref} />
     );
 
-    ref.current?.osInstance()?.update(true);
+    ref.current!.instance()!.update(true);
     expect(onUpdatedInitial).toHaveBeenCalledTimes(2);
     expect(onUpdated).toHaveBeenCalledTimes(2);
 
     // unregister works with `[]`, `null` or `undefined`
     rerender(<OverlayScrollbarsComponent events={{ updated: null }} ref={ref} />);
 
-    ref.current?.osInstance()?.update(true);
+    ref.current!.instance()!.update(true);
     expect(onUpdatedInitial).toHaveBeenCalledTimes(2);
     expect(onUpdated).toHaveBeenCalledTimes(2);
   });

packages/overlayscrollbars/src/initialization.ts

@@ -47,6 +47,7 @@ export type Initialization = {
   /**
    * Customizes which elements are generated and used.
    * If a function is passed to any of the fields, it receives the `target` element as its argument.
+   * Any passed function should be a "pure" function. (same input produces same output)
    */
   elements: {
     /**