(feat) add onIndexChange

README.md

@@ -84,6 +84,7 @@ Example: pass a footer component that contains a "previous" and "next" button to
 | startIndex | number          | Indicate the wizard to start at the given step             | ❌       | 0       |
 | header     | React.ReactNode | Header that is shown above the active step                 | ❌       |         |
 | footer     | React.ReactNode | Footer that is shown below the active stepstep             | ❌       |         |
+| onStepChange     | (stepIndex) | Callback that will be invoked with the new step index when the wizard changes steps             | ❌       |         |
   | wrapper  | React.React.ReactElement | Optional wrapper that is exclusively wrapped around the active step component. It is not wrapped around the `header` and `footer`             | ❌       |         |
 | children   | React.ReactNode | Each child component will be treated as an individual step | ✔️       |
 

playground/modules/wizard/simple/index.tsx

@@ -7,7 +7,10 @@ import Section from '../../common/section';
 const SimpleSection: React.FC = () => {
   return (
     <Section title="Simple wizard" description="mix of async and sync steps">
-      <Wizard footer={<Footer />}>
+      <Wizard
+        footer={<Footer />}
+        onStepChange={(stepIndex) => alert(`New step index is ${stepIndex}`)}
+      >
         <AsyncStep number={1} />
         <Step number={2} />
         <AsyncStep number={3} />

src/types.ts

@@ -9,7 +9,6 @@ export type WizardProps = {
   startIndex?: number;
   /**
    * Optional wrapper that is exclusively wrapped around the active step component. It is not wrapped around the `header` and `footer`
-   *
    * @example With `framer-motion` - `<AnimatePresence />`
    * ```jsx
    * <Wizard wrapper={<AnimatePresence exitBeforeEnter />}>
@@ -18,6 +17,8 @@ export type WizardProps = {
    * ```
    */
   wrapper?: React.ReactElement;
+  /** Callback that will be invoked with the new step index when the wizard changes steps */
+  onStepChange?: (stepIndex: number) => void;
 };
 
 export type WizardValues = {
@@ -31,13 +32,11 @@ export type WizardValues = {
   previousStep: () => void;
   /**
    * Go to the given step index
-   *
    * @param stepIndex The step index, starts at 0
    */
   goToStep: (stepIndex: number) => void;
   /**
    * Attach a callback that will be called when calling `nextStep()`
-   *
    * @param handler Can be either sync or async
    */
   handleStep: (handler: Handler) => void;

src/wizard.tsx

@@ -5,7 +5,14 @@ import { Handler, WizardProps } from './types';
 import WizardContext from './wizardContext';
 
 const Wizard: React.FC<React.PropsWithChildren<WizardProps>> = React.memo(
-  ({ header, footer, children, wrapper: Wrapper, startIndex = 0 }) => {
+  ({
+    header,
+    footer,
+    children,
+    onStepChange,
+    wrapper: Wrapper,
+    startIndex = 0,
+  }) => {
     const [activeStep, setActiveStep] = React.useState(startIndex);
     const [isLoading, setIsLoading] = React.useState(false);
     const hasNextStep = React.useRef(true);
@@ -16,24 +23,31 @@ const Wizard: React.FC<React.PropsWithChildren<WizardProps>> = React.memo(
     hasNextStep.current = activeStep < stepCount - 1;
     hasPreviousStep.current = activeStep > 0;
 
-    const goToNextStep = React.useRef(() => {
+    const goToNextStep = React.useCallback(() => {
       if (hasNextStep.current) {
-        setActiveStep((activeStep) => activeStep + 1);
+        const newActiveStepIndex = activeStep + 1;
+
+        setActiveStep(newActiveStepIndex);
+        onStepChange?.(newActiveStepIndex);
       }
-    });
+    }, [activeStep, onStepChange]);
 
-    const goToPreviousStep = React.useRef(() => {
+    const goToPreviousStep = React.useCallback(() => {
       if (hasPreviousStep.current) {
         nextStepHandler.current = null;
-        setActiveStep((activeStep) => activeStep - 1);
+        const newActiveStepIndex = activeStep - 1;
+
+        setActiveStep(newActiveStepIndex);
+        onStepChange?.(newActiveStepIndex);
       }
-    });
+    }, [activeStep, onStepChange]);
 
     const goToStep = React.useCallback(
       (stepIndex: number) => {
         if (stepIndex >= 0 && stepIndex < stepCount) {
           nextStepHandler.current = null;
           setActiveStep(stepIndex);
+          onStepChange?.(stepIndex);
         } else {
           if (__DEV__) {
             logger.log(
@@ -46,35 +60,35 @@ const Wizard: React.FC<React.PropsWithChildren<WizardProps>> = React.memo(
           }
         }
       },
-      [stepCount],
+      [stepCount, onStepChange],
     );
 
     // Callback to attach the step handler
     const handleStep = React.useRef((handler: Handler) => {
       nextStepHandler.current = handler;
     });
 
-    const doNextStep = React.useRef(async () => {
+    const doNextStep = React.useCallback(async () => {
       if (hasNextStep.current && nextStepHandler.current) {
         try {
           setIsLoading(true);
           await nextStepHandler.current();
           setIsLoading(false);
           nextStepHandler.current = null;
-          goToNextStep.current();
+          goToNextStep();
         } catch (error) {
           setIsLoading(false);
           throw error;
         }
       } else {
-        goToNextStep.current();
+        goToNextStep();
       }
-    });
+    }, [goToNextStep]);
 
     const wizardValue = React.useMemo(
       () => ({
-        nextStep: doNextStep.current,
-        previousStep: goToPreviousStep.current,
+        nextStep: doNextStep,
+        previousStep: goToPreviousStep,
         handleStep: handleStep.current,
         isLoading,
         activeStep,
@@ -83,7 +97,14 @@ const Wizard: React.FC<React.PropsWithChildren<WizardProps>> = React.memo(
         isLastStep: !hasNextStep.current,
         goToStep,
       }),
-      [isLoading, activeStep, stepCount, goToStep],
+      [
+        doNextStep,
+        goToPreviousStep,
+        isLoading,
+        activeStep,
+        stepCount,
+        goToStep,
+      ],
     );
 
     const activeStepContent = React.useMemo(() => {

test/useWizard.test.tsx

@@ -276,4 +276,58 @@ describe('useWizard', () => {
     expect(result.current.isFirstStep).toBe(false);
     expect(result.current.isLastStep).toBe(true);
   });
+
+  describe('onStepChange()', () => {
+    const renderUseWizardHook = (
+      onStepChange: (index: number) => void,
+      startIndex = 0,
+    ) => {
+      return renderHook(() => useWizard(), {
+        initialProps: {
+          startIndex,
+          onStepChange,
+        },
+        wrapper: ({ children, startIndex, onStepChange }) => (
+          <Wizard startIndex={startIndex} onStepChange={onStepChange}>
+            <p>step 1 {children}</p>
+            <p>step 2 {children}</p>
+            <p>step 3 {children}</p>
+          </Wizard>
+        ),
+      });
+    };
+
+    test('should invoke onStepChange when nextStep is called', async () => {
+      const onStepChange = jest.fn();
+      const { result, waitForNextUpdate } = renderUseWizardHook(onStepChange);
+
+      result.current.nextStep();
+
+      await waitForNextUpdate();
+
+      expect(onStepChange).toHaveBeenCalledWith(1);
+    });
+
+    test('should invoke onStepChange when previousStep is called', async () => {
+      const onStepChange = jest.fn();
+      const { result } = renderUseWizardHook(onStepChange, 1);
+
+      act(() => {
+        result.current.previousStep();
+      });
+
+      expect(onStepChange).toHaveBeenCalledWith(0);
+    });
+
+    test('should invoke onStepChange when goToStep is called', async () => {
+      const onStepChange = jest.fn();
+      const { result } = renderUseWizardHook(onStepChange);
+
+      act(() => {
+        result.current.goToStep(1);
+      });
+
+      expect(onStepChange).toHaveBeenCalledWith(1);
+    });
+  });
 });