Intermediate code explainers

typescript

type CloneInput = Record<string, unknown> | unknown[] | Map<unknown, unknown> | Set<unknown>;
 
export function deepClone<T>(value: T): T {
  if (typeof structuredClone === "function") {

Building a deepClone with cycle safety

recursion deep-copy cycle-detection

Intermediate 8 steps

rust

use std::fs::File;
use std::io::{self, BufRead, BufReader};
use std::path::Path;

Buffered log scanning in Rust

buffered-io error-handling streaming

Intermediate 9 steps

python

from functools import wraps
 
 
def memoize(func):

Building a memoize decorator in Python

decorators closures memoization

Intermediate 5 steps

php

<?php
 
namespace App\Support;

Grouping records with array_reduce in PHP

array-reduce grouping higher-order-functions

Intermediate 6 steps

java

@Component
public class RequestTimingInterceptor implements HandlerInterceptor {
 
    private static final Logger log = LoggerFactory.getLogger(RequestTimingInterceptor.class);

How a Spring HandlerInterceptor times requests

interceptor request-lifecycle logging

Intermediate 6 steps

ruby

class Post < ApplicationRecord
  before_validation :generate_slug, on: :create
 
  validates :slug, presence: true, uniqueness: true

How a Rails model builds unique slugs

slugs callbacks validations

Intermediate 7 steps

go

package middleware
 
import (
	"errors"

Centralized error handling in Gin

middleware error-handling custom-errors

Intermediate 8 steps

typescript

import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { Observable, shareReplay } from 'rxjs';

Caching HTTP config in an Angular service

caching observables dependency-injection

Intermediate 6 steps

rust

use axum::{
    extract::{Path, State},
    routing::{get, post},
    Json, Router,

Building a nested REST API router in Axum

routing extractors shared-state

Intermediate 8 steps

php

<?php
 
namespace App\Console;

How task scheduling works in Laravel

scheduling cron fluent-api

Intermediate 7 steps

javascript

import { useState, useEffect } from "react";
 
export function useUser(userId) {
  const [user, setUser] = useState(null);

How a data-fetching hook works in React

custom-hooks data-fetching abortcontroller

Intermediate 8 steps

php

<?php
 
namespace App\Policies;

How authorization policies gate updates in Laravel

authorization policies access control

Intermediate 7 steps

typescript

import {
  CACHE_MANAGER,
  CacheInterceptor,
} from '@nestjs/cache-manager';

A tenant-aware HTTP cache in NestJS

caching interceptors multi-tenancy

Intermediate 7 steps

java

@RestController
@RequestMapping("/api/products")
public class ProductController {

How a paginated REST controller works in Spring

pagination dto-mapping dependency-injection

Intermediate 8 steps

python

import re
from datetime import datetime
from dataclasses import dataclass

Parsing access logs with named regex groups

regex named-groups dataclasses

Intermediate 6 steps

php

<?php
 
final class ProductRepository
{

Safe SQL pagination with PDO in PHP

pagination input-validation prepared-statements

Intermediate 7 steps

rust

use axum::{
    extract::State,
    http::StatusCode,
    response::IntoResponse,

An async job queue handler in Axum

background-jobs async http-202

Intermediate 9 steps

ruby

module TextAnalysis
  module_function
 
  WORD_PATTERN = /[\p{Alpha}']+/

Building a word-frequency analyzer in Ruby

text processing regex enumerable

Intermediate 8 steps