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Reusable useDebouncedValue Hook
Delay a rapidly changing value before triggering searches, validation, or API requests.
'use client';
import { useEffect, useState } from 'react';
export function useDebouncedValue<T>(
value: T,
delay = 300,
): T {
const [debouncedValue, setDebouncedValue] = useState(value);
useEffect(() => {
Dynamic Page with notFound
Render the nearest not-found UI when a requested App Router record does not exist.
// app/products/[id]/page.tsx
import { notFound } from 'next/navigation';
type PageProps = {
params: Promise<{
id: string;
}>;
};
export default async function ProductPage({
params,
}: PageProps) {
const { id } = await params;
Lazy Component Loading with Suspense
Load a large component only when it is rendered and show a fallback during download.
'use client';
import { lazy, Suspense, useState } from 'react';
const AnalyticsChart = lazy(
() => import('./analytics-chart'),
);
export function AnalyticsPanel() {
const [isOpen, setIsOpen] = useState(false);
return (
<section>
<buttonAccessible Form Fields with useId
Generate stable IDs for reusable form controls and accessible help text.
import { useId } from 'react';
type TextFieldProps = {
label: string;
name: string;
helpText?: string;
};
export function TextField({
label,
name,
helpText,
}: TextFieldProps) {
const inputId = useId();
const helpId = `${inputId}-help`;
Non-Blocking Tabs with useTransition
Switch expensive tab content without blocking urgent UI updates.
'use client';
import { useState, useTransition } from 'react';
const tabs = ['overview', 'activity', 'settings'] as const;
type Tab = (typeof tabs)[number];
export function DashboardTabs() {
const [activeTab, setActiveTab] = useState<Tab>('overview');Deferred Search Results with useDeferredValue
Keep a search input responsive while a larger result list updates at lower priority.
'use client';
import { useDeferredValue, useMemo, useState } from 'react';
type Product = {
id: number;
name: string;
};
export function ProductSearch({ products }: { products: Product[] }) {
const [query, setQuery] = useState('');Optimistic Todo List with useOptimistic
Show a new todo immediately while the asynchronous save operation completes in the background.
'use client';
import { startTransition, useOptimistic, useState } from 'react';
type Todo = {
id: string;
text: string;
pending?: boolean;
};
type Props = {
initialTodos: Todo[];
createTodo: (text: string) => Promise<Todo>;
};
React Form Validation with useActionState
Manage form validation, submission status, and server-style action results with React useActionState.
'use client';
import { useActionState } from 'react';
type FormState = {
message: string;
errors: {
email?: string;
};
};
const initialState: FormState = {
message: '',
errors: {},
};
async function subscribe(
previousState: FormState,Fork: Async LRU Cache with TTL and Eviction Callback
Implements an asynchronous Least Recently Used (LRU) cache with a fixed size, optional time-to-live (TTL) for entries, background expiration...
import asyncio
import time
from collections import OrderedDict
class AsyncLRUCache:
def __init__(self, maxsize):
self.maxsize = maxsize
self.cache = OrderedDict() # key -> (value, expire_time)
self.lock = asyncio.Lock()
cURL GET Request in PHP
Call an external API with cURL and decode the JSON response.
<?php
$ch = curl_init('https://api.example.com/items');
curl_setopt_array($ch, [
CURLOPT_RETURNTRANSFER => true,
CURLOPT_TIMEOUT => 10,
]);
$responseBody = curl_exec($ch);
$statusCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);PHP Read JSON Request Body
Read and validate a JSON request body in PHP.
<?php
$rawBody = file_get_contents('php://input');
$data = json_decode($rawBody, true);
if (!is_array($data) || json_last_error() !== JSON_ERROR_NONE) {
http_response_code(400);
echo json_encode(['error' => 'Invalid JSON body.']);
exit;
}
PHP JSON Response Helper
Return a JSON response from a small PHP endpoint.
<?php
function json_response(array $payload, int $status = 200): void
{
http_response_code($status);
header('Content-Type: application/json; charset=utf-8');
echo json_encode($payload, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);
exit;
}
Fetch POST JSON Request
Send JSON data to a backend endpoint with fetch.
async function createNote(note) {
const response = await fetch('/api/notes', {
method: 'POST',
headers: {
'Content-Type': 'application/json'
},
body: JSON.stringify(note)
});
if (!response.ok) {Fetch GET Request
Load JSON from an API endpoint with async and await.
async function searchSnippets(query) {
const url = `/api/snippets?search=${encodeURIComponent(query)}`;
const response = await fetch(url);
if (!response.ok) {
throw new Error('Search request failed.');
}
Card Grid with Equal Height Cards
Create a responsive Bootstrap card grid where cards keep equal height.
<div class="row g-4">
<div class="col-md-6 col-lg-4">
<div class="card h-100">
<div class="card-body d-flex flex-column">
<h5 class="card-title">Feature title</h5>Offcanvas Sidebar Layout
Open a mobile-friendly offcanvas sidebar with Bootstrap.
<button class="btn btn-outline-secondary" data-bs-toggle="offcanvas" data-bs-target="#accountMenu">
Menu
</button>
<div class="offcanvas offcanvas-start" tabindex="-1" id="accountMenu">
<div class="offcanvas-header">Responsive Navbar Starter
A simple Bootstrap responsive navbar with collapse behavior.
<nav class="navbar navbar-expand-lg bg-body-tertiary">
<div class="container">
<a class="navbar-brand" href="/">CodShot</a>
<button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#mainNav">Bootstrap Modal Form Skeleton
A small Bootstrap 5 modal with a form and submit button.
<button class="btn btn-primary" data-bs-toggle="modal" data-bs-target="#newItemModal">
New item
</button>
<div class="modal fade" id="newItemModal" tabindex="-1" aria-hidden="true">
<div class="modal-dialog">Bootstrap Toast Notification
Show a Bootstrap 5 toast message from JavaScript.
<button class="btn btn-primary" id="showToastBtn">Show toast</button>
<div class="toast-container position-fixed bottom-0 end-0 p-3">
<div id="demoToast" class="toast" role="status" aria-live="polite" aria-atomic="true">
<div class="toast-header">Save UI State to localStorage
Remember a simple UI preference in localStorage.
const checkbox = document.querySelector('#compactMode');
const savedValue = localStorage.getItem('compactMode');
checkbox.checked = savedValue === '1';
document.body.classList.toggle('compact', checkbox.checked);
checkbox.addEventListener('change', () => {Fetch JSON with Error Handling
Fetch JSON data and handle HTTP errors cleanly.
async function loadProfile() {
const response = await fetch('/api/profile');
if (!response.ok) {
throw new Error(`Request failed: ${response.status}`);
}
return await response.json();
}
loadProfile()Simple Form Validation
Validate a small form before submitting it.
const form = document.querySelector('#contactForm');
const emailInput = document.querySelector('#email');
const messageBox = document.querySelector('#formMessage');
form.addEventListener('submit', (event) => {
messageBox.textContent = '';
Event Delegation for Buttons
Handle clicks for many dynamic buttons with one event listener.
const list = document.querySelector('#todoList');
list.addEventListener('click', (event) => {
const button = event.target.closest('[data-action]');
if (!button) return;
const item = button.closest('.todo-item');
Toggle Class on Click
Toggle a CSS class on an element when a button is clicked.
const button = document.querySelector('#menuButton');
const menu = document.querySelector('#menu');
button.addEventListener('click', () => {
menu.classList.toggle('is-open');
});