Intermediate code explainers

python

from functools import wraps
 
from django.core.cache import cache
from django.http import JsonResponse

Building a rate-limit decorator in Django

decorators rate limiting caching

Intermediate 7 steps

ruby

class WeightedSampler
  def initialize(weights)
    @entries = weights.to_a
    @total = @entries.sum { |_, w| w }

Weighted random sampling with binary search

weighted-sampling binary-search cumulative-sum

Intermediate 7 steps

go

package middleware
 
import (
	"strconv"

Instrumenting a Gin API with Prometheus

middleware observability metrics

Intermediate 6 steps

php

<?php
 
namespace App\Http\Requests;

How a Laravel FormRequest validates invoices

validation authorization form-request

Intermediate 6 steps

typescript

import { Controller, Get } from '@nestjs/common';
import {
  HealthCheck,
  HealthCheckService,

Liveness vs readiness probes in NestJS

health-checks dependency-injection observability

Intermediate 6 steps

java

@Service
public class PaymentGatewayClient {
 
    private static final Logger log = LoggerFactory.getLogger(PaymentGatewayClient.class);

Resilient payment calls in Spring

circuit breaker retry fault tolerance

Intermediate 7 steps

python

import os
import time
from pathlib import Path

Polling a directory for file changes in Python

polling filesystem set-operations

Intermediate 8 steps

ruby

class HealthController < ApplicationController
  skip_before_action :authenticate_user!, raise: false
  skip_forgery_protection

Building a health check endpoint in Rails

health-check monitoring error-handling

Intermediate 7 steps

php

<?php
 
namespace App\Config;

Writing a .env file loader in PHP

parsing environment-variables configuration

Intermediate 9 steps

java

@Target(ElementType.PARAMETER)
@Retention(RetentionPolicy.RUNTIME)
public @interface CurrentUser {
}

Injecting the current user in Spring MVC

annotations dependency-injection security

Intermediate 8 steps

rust

use axum::{extract::{Path, State}, http::StatusCode, Json};
use serde::Serialize;
use std::sync::Arc;

Concurrent dashboard aggregation in Axum

concurrency error-handling graceful-degradation

Intermediate 7 steps

javascript

'use client';
 
import { useOptimistic, useTransition } from 'react';
import { toggleLike } from '@/app/actions/likes';

Optimistic like buttons in Next.js

optimistic-ui react-hooks server-actions

Intermediate 7 steps

javascript

const express = require('express');
const router = express.Router();
 
router.get('/articles/:slug', async (req, res, next) => {

Content negotiation with res.format in Express

content-negotiation routing error-handling

Intermediate 9 steps

rust

use axum::{
    extract::{Path, State},
    http::{header, HeaderMap, StatusCode},
    response::{IntoResponse, Response},

Optimistic concurrency with ETags in Axum

optimistic-concurrency etag http-headers

Intermediate 8 steps

java

public final class TokenBucketRateLimiter {
 
    private final long capacity;
    private final double refillTokensPerNano;

How a token bucket rate limiter works

rate-limiting concurrency token-bucket

Intermediate 8 steps

go

package handlers
 
import (
	"net/http"

Struct-level validation for partial updates in Gin

validation struct-tags partial-update

Intermediate 7 steps

typescript

import {
  Controller,
  Post,
  Headers,

Verifying Stripe webhooks in NestJS

webhooks signature-verification event-handling

Intermediate 7 steps

javascript

function makeTableSorter(rows) {
  const state = { key: null, dir: 1 };
 
  const compareBy = (key) => (a, b) => {

Building a stateful table sorter in JavaScript

closures stable-sort comparators

Intermediate 7 steps