React Suspense 与资源预加载：实现无缝用户体验的预测性数据加载

            // ProductComponent.js
import React, { Suspense, useState, useEffect } from 'react';

const fetchData = (productId) => {
  // Simulate an API call
  return new Promise((resolve) => {
    setTimeout(() => {
      resolve({ id: productId, name: `Product ${productId}`, description: 'A fantastic product.', price: 29.99 });
    }, 1500); // Simulate a 1.5-second delay
  });
};

const Product = React.lazy(() =>
  import('./ProductDetails').then(module => ({
    default: module.ProductDetails
  }))
);

function ProductComponent({ productId }) {
  const [product, setProduct] = useState(null);
  const [error, setError] = useState(null);

  useEffect(() => {
    const loadProduct = async () => {
      try {
        const data = await fetchData(productId);
        setProduct(data);
      } catch (err) {
        setError(err);
      }
    };

    loadProduct();
  }, [productId]);

  if (error) {
    return 
Error loading product: {error.message}
;
  }

  if (!product) {
    return 
Loading...
;
  }

  return ;
}

export default ProductComponent;

            

              
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// ProductDetails.js
import React from 'react';

function ProductDetails({ product }) {
  return (
    

      
{product.name}
      
{product.description}
      
Price: ${product.price}
    
  );
}

export default ProductDetails;

            

              
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// useProductData.js (Custom Hook for Data Fetching and Preloading)
import { useState, useEffect, useTransition } from 'react';

const fetchData = (productId) => {
  return new Promise((resolve) => {
    setTimeout(() => {
      resolve({ id: productId, name: `Preloaded Product ${productId}`, description: 'A proactively loaded product.', price: 39.99 });
    }, 1000); // Simulate a 1-second delay
  });
};

export function useProductData(productId) {
  const [product, setProduct] = useState(null);
  const [error, setError] = useState(null);
  const [isPending, startTransition] = useTransition();

  useEffect(() => {
    const loadProduct = async () => {
      try {
        const data = await fetchData(productId);
        startTransition(() => {
            setProduct(data);
        });
      } catch (err) {
        setError(err);
      }
    };

    loadProduct();
  }, [productId, startTransition]);

  return { product, error, isPending };
}

            

              
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// ProductComponent.js
import React, { Suspense, lazy } from 'react';
import { useProductData } from './useProductData';

const ProductDetails = lazy(() => import('./ProductDetails'));

function ProductComponent({ productId }) {
  const { product, error, isPending } = useProductData(productId);

  if (error) {
    return 
Error loading product: {error.message}
;
  }

  return (
    Loading Product Details...