Code Snippets

1400">import { useState, useEffect } 400">from 'react';
2 
3400">function useLocalStorage<T>(key: 400">string, initialValue: T) {
4  400">const [storedValue, setStoredValue] = useState<T>(() => {
5    400">try {
6      400">const item = window.localStorage.300">getItem(key);
7      400">return item ? JSON.300">parse(item) : initialValue;
8    } 400">catch (error) {
9      console.300">error(error);
10      400">return initialValue;
11    }
12  });
13 
14  400">const setValue = (value: T | ((val: T) => T)) => {
15    400">try {
16      400">const valueToStore = value 400">instanceof Function ? 300">value(storedValue) : value;
17      300">setStoredValue(valueToStore);
18      window.localStorage.300">setItem(key, JSON.300">stringify(valueToStore));
19    } 400">catch (error) {
20      console.300">error(error);
21    }
22  };
23 
24  400">return [storedValue, setValue] 400">as 400">const;
25}
26 
27// Usage
28400">const [theme, setTheme] = 300">useLocalStorage('theme', 'light');

1400">import { NextApiRequest, NextApiResponse } 400">from 'next';
2400">import { z } 400">from 'zod';
3 
4400">const schema = z.400">object({
5  email: z.400">string().300">email(),
6  name: z.400">string().300">min(2),
7});
8 
9400">export 400">default 400">async 400">function 300">handler(
10  req: NextApiRequest,
11  res: NextApiResponse
12) {
13  400">if (req.method !== 'POST') {
14    400">return res.300">status(405).300">json({ message: 'Method not allowed' });
15  }
16 
17  400">try {
18    400">const validatedData = schema.300">parse(req.body);
19    
20    // Process data...
21    400">const result = 400">await 300">processData(validatedData);
22    
23    400">return res.300">status(200).300">json({ success: 400">true, data: result });
24  } 400">catch (error) {
25    400">if (error 400">instanceof z.ZodError) {
26      400">return res.300">status(400).300">json({
27        success: 400">false,
28        errors: error.errors.300">map(e => ({
29          path: e.path.300">join('.'),
30          message: e.message
31        }))
32      });
33    }
34    
35    console.300">error('API Error:', error);
36    400">return res.300">status(500).300">json({
37      success: 400">false,
38      message: 'Internal server error'
39    });
40  }
41}

1type DeepPartial<T> = T 400">extends 400">object ? {
2  [P in keyof T]?: DeepPartial<T[P]>;
3} : T;
4 
5// Usage
6interface User {
7  id: 400">number;
8  profile: {
9    name: 400">string;
10    address: {
11      street: 400">string;
12      city: 400">string;
13    };
14  };
15}
16 
17400">const partialUser: DeepPartial<User> = {
18  profile: {
19    address: {
20      city: "New York"
21    }
22  }
23};

1400">function 300">Card({ title, description, icon }: CardProps) {
2  400">return (
3    <div className="
4      bg-white dark:bg-slate-800
5      rounded-xl
6      border border-slate-200 dark:border-slate-700
7      p-6
8      shadow-sm hover:shadow-md
9      transition-all duration-200
10    ">
11      <div className="flex items-start gap-4">
12        <div className="
13          p-3
14          rounded-lg
15          bg-blue-100 dark:bg-blue-900/30
16          text-blue-600 dark:text-blue-400
17        ">
18          {icon}
19        </div>
20        <div className="flex-1">
21          <h3 className="
22            text-lg font-semibold
23            text-slate-900 dark:text-white
24            mb-2
25          ">
26            {title}
27          </h3>
28          <p className="
29            text-slate-600 dark:text-slate-400
30            leading-relaxed
31          ">
32            {description}
33          </p>
34        </div>
35      </div>
36    </div>
37  );
38}

1400">import { z } 400">from 'zod';
2 
3400">const userSchema = z.400">object({
4  role: z.300">enum(['user', 'admin', 'moderator']),
5  email: z.400">string().300">email(),
6  permissions: z.300">array(z.400">string()).300">optional(),
7})
8.300">refine(
9  (data) => {
10    400">if (data.role === 'admin' && (!data.permissions || data.permissions.length === 0)) {
11      400">return 400">false;
12    }
13    400">return 400">true;
14  },
15  {
16    message: 'Admins must have at least one permission',
17    path: ['permissions']
18  }
19)
20.300">transform((data) => ({
21  ...data,
22  createdAt: 400">new 400">Date().300">toISOString(),
23  isActive: 400">true
24}));
25 
26// Usage
27400">const validated = userSchema.300">parse({
28  role: 'admin',
29  email: 'admin@example.com',
30  permissions: ['read', 'write']
31});

1400">import { useInfiniteQuery } 400">from '@tanstack/react-query';
2 
3400">function 300">useInfinitePosts() {
4  400">return 300">useInfiniteQuery({
5    queryKey: ['posts'],
6    queryFn: 400">async ({ pageParam = 1 }) => {
7      400">const response = 400">await 300">fetch(`/api/posts?page=${pageParam}`);
8      400">return response.300">json();
9    },
10    getNextPageParam: (lastPage, allPages) => {
11      400">if (lastPage.hasNextPage) {
12        400">return allPages.length + 1;
13      }
14      400">return 400">undefined;
15    },
16    initialPageParam: 1,
17  });
18}
19 
20400">function 300">PostsList() {
21  400">const { data, fetchNextPage, hasNextPage, isFetchingNextPage } = 300">useInfinitePosts();
22  
23  300">useEffect(() => {
24    400">const handleScroll = () => {
25      400">if (
26        window.innerHeight + window.scrollY >= document.body.offsetHeight - 500 &&
27        hasNextPage &&
28        !isFetchingNextPage
29      ) {
30        300">fetchNextPage();
31      }
32    };
33    
34    window.300">addEventListener('scroll', handleScroll);
35    400">return () => window.300">removeEventListener('scroll', handleScroll);
36  }, [hasNextPage, isFetchingNextPage, fetchNextPage]);
37  
38  400">return (
39    <div>
40      {data?.pages.300">map((page, pageIndex) => (
41        <div key={pageIndex}>
42          {page.posts.300">map((post) => (
43            <PostCard key={post.id} post={post} />
44          ))}
45        </div>
46      ))}
47      {isFetchingNextPage && <LoadingSpinner />}
48    </div>
49  );
50}