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go 
package auth
 
import (
	"net/http"

Setting and reading secure session cookies in Go

cookies session-management security
Intermediate 6 steps
rust 
use std::cmp::Ordering;
use std::str::FromStr;
 
#[derive(Debug, Clone, PartialEq, Eq)]

Parsing and ordering semantic versions in Rust

parsing trait-implementation ordering
Intermediate 8 steps
php 
<?php
 
namespace App\Http\Middleware;
 

Idempotent requests with Laravel middleware

idempotency middleware caching
Advanced 8 steps
javascript 
'use client';
 
import { useEffect } from 'react';
import * as Sentry from '@sentry/nextjs';

How a Next.js error boundary recovers

error-boundary error-handling observability
Intermediate 8 steps
ruby 
class Registration < ApplicationRecord
  belongs_to :event
 
  validates :email, presence: true, format: { with: URI::MailTo::EMAIL_REGEXP }

Validating registrations in Rails

validations i18n error-handling
Intermediate 8 steps
python 
from django.contrib.postgres.search import SearchQuery, SearchRank, SearchVector
from django.core.cache import cache
from django.db.models import F
from django.http import JsonResponse

Ranked full-text search in Django

full-text-search debouncing caching
Advanced 9 steps
java 
@Repository
public interface OrderRepository extends JpaRepository<Order, Long> {
 
    @Query("""

Keyset pagination with Spring Data JPA

pagination cursor jpa
Advanced 8 steps
typescript 
import { CanActivate, ExecutionContext, Injectable, UnauthorizedException } from '@nestjs/common';
import { GqlExecutionContext } from '@nestjs/graphql';
import { Reflector } from '@nestjs/core';
import { JwtService } from '@nestjs/jwt';

How a GraphQL auth guard works in NestJS

authentication authorization jwt
Intermediate 7 steps
python 
import os
from datetime import timedelta
 
 

Class-based config in a Flask app factory

configuration app-factory inheritance
Intermediate 7 steps
typescript 
type ResizeCallback = (size: { width: number; height: number }) => void;
 
export function observeResize(callback: ResizeCallback, delay = 150) {
  let timeoutId: ReturnType<typeof setTimeout> | undefined;

Debouncing window resize in TypeScript

debounce closures event-listeners
Intermediate 6 steps
ruby 
class ApacheLogParser
  LINE_PATTERN = /\A(?<ip>\S+)\s\S+\s\S+\s\[(?<time>[^\]]+)\]\s"(?<method>[A-Z]+)\s(?<path>\S+)\s(?<protocol>[^"]+)"\s(?<status>\d{3})\s(?<bytes>\d+|-)/
 
  TIME_FORMAT = "%d/%b/%Y:%H:%M:%S %z"

Parsing Apache logs with named captures

regex named-captures parsing
Intermediate 6 steps
go 
package middleware
 
import (
	"net/http"

A maintenance-mode gate in Gin

middleware atomic-flag concurrency
Intermediate 8 steps
php 
<?php
 
namespace App\Services;
 

Batch image resizing with PHP GD

image-processing constructor-promotion match-expression
Intermediate 10 steps
java 
public record FixedWidthField(String name, int start, int end) {
 
    public String extract(String line) {
        int from = Math.min(start, line.length());

Parsing fixed-width text in Java

records parsing streams
Intermediate 7 steps
javascript 
const MAX_BATCH_SIZE = 20;
const FLUSH_INTERVAL = 5000;
const ENDPOINT = '/api/analytics';
 

Batching analytics events in the browser

batching buffering sendbeacon
Intermediate 10 steps
rust 
use axum::{
    extract::State,
    routing::{get, post, MethodRouter},
    Json, Router,

Self-documenting routes in Axum

builder-pattern closures shared-state
Intermediate 8 steps
python 
import time
 
from flask import Flask, g, request
 

Timing requests with Flask hooks

middleware request-lifecycle instrumentation
Intermediate 5 steps
typescript 
import { Injectable, Logger, OnApplicationShutdown } from '@nestjs/common';
import { InjectRedis } from '@nestjs-modules/ioredis';
import Redis from 'ioredis';
import { DataSource } from 'typeorm';

Graceful shutdown hooks in NestJS

graceful-shutdown lifecycle-hooks dependency-injection
Intermediate 7 steps