Code Explainers
Intermediate code explainers
javascript
async function fetchAllPages(baseUrl, { pageSize = 100, headers = {} } = {}) { const results = []; let cursor = null;
Cursor-based pagination with fetch
pagination
async-await
fetch
Intermediate
6 steps
rust
use std::collections::HashMap; pub fn word_frequencies(text: &str) -> HashMap<String, usize> { let mut counts: HashMap<String, usize> = HashMap::new();
Counting and ranking words in Rust
hashmap
iterators
sorting
Intermediate
7 steps
php
<?php namespace App\Security;
A fixed-window rate limiter on APCu
rate-limiting
fixed-window
caching
Intermediate
8 steps
python
from flask import Blueprint, render_template, redirect, url_for, flash from flask_login import login_required, current_user from flask_wtf import FlaskForm from wtforms import StringField, TextAreaField, SubmitField
Handling a post form with a Flask Blueprint
blueprints
form-validation
post-redirect-get
Intermediate
7 steps
go
package storage import ( "bufio"
Streaming file downloads safely in Go
http
streaming
path-traversal
Intermediate
7 steps
typescript
type SearchResult = { id: string; title: string; };
Cancelling stale searches with AbortController
abortcontroller
cancellation
async
Intermediate
7 steps
java
public class WorkPipeline { private final BlockingQueue<Task> queue = new LinkedBlockingQueue<>(1000); private static final Task POISON = new Task(-1, null); private final ExecutorService consumers = Executors.newFixedThreadPool(4);
A producer-consumer pipeline in Java
concurrency
producer-consumer
blocking-queue
Intermediate
8 steps
ruby
class OrderConfirmationJob < ApplicationJob queue_as :mailers retry_on Net::OpenTimeout, wait: :polynomially_longer, attempts: 5
Resilient background jobs in Rails
background-jobs
retries
idempotency
Intermediate
8 steps
rust
use std::error::Error; use std::fmt; #[derive(Debug)]
Building a typed error enum in Rust
error-handling
enums
trait-implementation
Intermediate
9 steps
php
class PostController extends Controller { public function index(Request $request) {
Eager loading without N+1 in Laravel
eager-loading
n+1
query-builder
Intermediate
9 steps
python
import random import time import logging from functools import wraps
A retry decorator with exponential backoff
decorators
retry
exponential-backoff
Intermediate
6 steps
go
package webhooks import ( "crypto/hmac"
Verifying GitHub webhooks in Gin
hmac
webhooks
middleware
Intermediate
6 steps
rust
use std::time::Duration; use axum::{routing::get, Router}; use tokio::net::TcpListener;
Graceful shutdown in an Axum server
graceful-shutdown
signal-handling
async
Intermediate
8 steps
python
from django.db import models from django.utils import timezone
How soft deletes work in Django
soft-delete
querysets
managers
Intermediate
10 steps
php
class PostController extends Controller { public function index(Request $request): AnonymousResourceCollection {
Filtered, paginated JSON APIs in Laravel
eloquent
query-builder
api-resources
Intermediate
8 steps
javascript
import { useState, useEffect, useMemo } from 'react'; function useDebounce(value, delay = 300) { const [debounced, setDebounced] = useState(value);
Debounced search with cancellation in React
custom-hooks
debounce
abortcontroller
Intermediate
9 steps
java
package com.example.payments.config; import jakarta.validation.constraints.Min; import jakarta.validation.constraints.NotBlank;
Type-safe config with Spring records
configuration
validation
records
Intermediate
6 steps
ruby
module SoftDeletable extend ActiveSupport::Concern included do
How a soft-delete concern works in Rails
concerns
soft-delete
scopes
Intermediate
8 steps