Intermediate code explainers

go

package httputil
 
import (
	"net"

Safely extracting the real client IP in Go

security http ip-spoofing

Intermediate 7 steps

ruby

require "openssl"
require "base32"
 
class TOTP

How TOTP one-time codes work in Ruby

hmac authentication totp

Intermediate 7 steps

python

from typing import Any, Sequence, Mapping
 
 
def render_markdown_table(

Rendering an aligned Markdown table in Python

string formatting data transformation closures

Intermediate 8 steps

php

class TwoFactorController extends Controller
{
    public function show(Request $request): View|RedirectResponse
    {

Two-factor auth challenge flow in Laravel

authentication two-factor middleware

Intermediate 10 steps

java

public final class ImportOrganizer {
 
    private static final Pattern IMPORT_LINE =
            Pattern.compile("^import\\s+(static\\s+)?([\\w.]+(?:\\.\\*)?)\\s*;\\s*$");

Sorting Java imports with a regex pass

regex sorting text-processing

Intermediate 8 steps

typescript

import { Pipe, PipeTransform } from '@angular/core';
 
@Pipe({
  name: 'chunk',

A memoized chunk pipe in Angular

memoization weakmap pure-pipes

Intermediate 7 steps

go

package signup
 
var wizardCodec = securecookie.New(
	[]byte(os.Getenv("WIZARD_HASH_KEY")),

A cookie-backed signup wizard in Gin

cookies encryption multi-step-form

Intermediate 9 steps

python

from django.db import connections
from django.db.utils import OperationalError
from django.core.cache import caches
from django.http import JsonResponse

Building a health check endpoint in Django

health check monitoring database

Intermediate 7 steps

go

func UpdateArticle(store *ArticleStore) gin.HandlerFunc {
	return func(c *gin.Context) {
		id := c.Param("id")

Optimistic concurrency with If-Match in Gin

optimistic-locking http-preconditions etag

Intermediate 9 steps

python

from enum import Enum
from typing import Annotated
 
from fastapi import FastAPI, Query, Request, status

Custom validation error responses in FastAPI

validation error-handling enums

Intermediate 8 steps

javascript

function collapseConsecutiveLogs(lines, { keyFn = (l) => l.message } = {}) {
  const groups = [];
 
  for (const line of lines) {

Collapsing consecutive log lines in JavaScript

grouping run-length-encoding data-transformation

Intermediate 7 steps

typescript

import { Directive, Input, HostBinding, HostListener } from '@angular/core';
import { NG_VALIDATORS, Validator, AbstractControl, ValidationErrors } from '@angular/forms';
 
@Directive({

A custom range validator directive in Angular

form-validation directives accessibility

Intermediate 8 steps

php

<?php
 
namespace App\Models;

Storing JSON preferences in a Laravel model

eloquent casting json

Intermediate 7 steps

ruby

class AdminConstraint
  def self.matches?(request)
    new(request).matches?
  end

How routing constraints gate admin routes in Rails

routing authorization constraints

Intermediate 8 steps

java

package com.example.api.config;
 
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;

Configuring CORS in Spring MVC

cors configuration dependency-injection

Intermediate 6 steps

python

from fastapi import Depends, FastAPI, Header, HTTPException, status
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

Chaining tenant dependencies in FastAPI

dependency injection multi-tenancy authentication

Intermediate 7 steps

javascript

const express = require('express');
const crypto = require('crypto');
const router = express.Router();

Optimistic locking with ETags in Express

optimistic-locking etag conditional-requests

Intermediate 7 steps

rust

use base64::{engine::general_purpose::URL_SAFE_NO_PAD, Engine};
use serde::{Deserialize, Serialize};
use time::OffsetDateTime;
use uuid::Uuid;

Opaque pagination cursors in Rust

pagination serialization base64

Intermediate 8 steps