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Infinite Scroll with IntersectionObserver
Load the next page when a sentinel approaches the viewport and prevent duplicate requests.
const sentinel = document.querySelector('[data-load-more]');
let page = 1;
let isLoading = false;
let hasMore = true;
const observer = new IntersectionObserver(
async (entries) => {
const entry = entries[0];
Typed JSON Fetch Helper
Wrap fetch with JSON parsing, typed responses, and useful HTTP error messages.
type ApiErrorBody = {
message?: string;
};
export async function fetchJson<T>(
input: RequestInfo | URL,
init?: RequestInit,
): Promise<T> {
const response = await fetch(input, {
...init,
headers: {
Accept: 'application/json',Async Generator for Paginated API Data
Iterate through paginated API responses without loading every page into memory.
type Page<T> = {
items: T[];
nextCursor: string | null;
};
export async function* paginate<T>(
buildUrl: (cursor: string | null) => string,
): AsyncGenerator<T, void, void> {
let cursor: string | null = null;
do {Process Mixed Results with Promise.allSettled
Run independent asynchronous tasks and keep both successful and failed outcomes.
async function loadDashboardResources() {
const requests = [
fetch('/api/profile').then((response) => response.json()),
fetch('/api/projects').then((response) => response.json()),
fetch('/api/notifications').then((response) => response.json()),Next.js Route Handler with JSON Validation
Validate a JSON request body and return typed responses from an App Router Route Handler.
// app/api/tasks/route.ts
import { NextResponse } from 'next/server';
type CreateTaskBody = {
title?: unknown;
};
export async function POST(request: Request) {
let body: CreateTaskBody;
try {
body = await request.json();
} catch {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.');
}
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()Safe JSON Load
Load JSON data from a file and handle invalid JSON safely.
import json
from pathlib import Path
file_path = Path("settings.json")
try:
data = json.loads(file_path.read_text(encoding="utf-8"))
print(data)
except FileNotFoundError:
print("settings.json was not found")
except json.JSONDecodeError:Simple CSV Reader
Read a CSV file with headers and print selected columns.
import csv
with open("students.csv", newline="", encoding="utf-8") as file:
reader = csv.DictReader(file)
for row in reader:
name = row.get("name", "")
grade = row.get("grade", "")
print(f"{name}: {grade}")Count Word Frequency
Count how often each word appears in a short text.
text = "python is fun and python is useful"
words = text.lower().split()
counts = {}
for word in words:
counts[word] = counts.get(word, 0) + 1
for word, count in counts.items():
print(word, count)Filter Even Numbers
Filter even numbers from a list using a simple list comprehension.
numbers = [3, 8, 12, 15, 20, 21, 30]
even_numbers = [number for number in numbers if number % 2 == 0]
print(even_numbers)Read Text File Lines
Read a text file line by line and remove the newline characters.
from pathlib import Path
file_path = Path("notes.txt")
if not file_path.exists():
print("File not found")
else:
lines = file_path.read_text(encoding="utf-8").splitlines()
for line_number, line in enumerate(lines, start=1):Save and Load JSON from localStorage
A safe small helper for storing JSON data in localStorage.
function saveJson(key, value) {
localStorage.setItem(key, JSON.stringify(value));
}
function loadJson(key, fallback = null) {
try {
const raw = localStorage.getItem(key);
return raw ? JSON.parse(raw) : fallback;
} catch (error) {