Intermediate code explainers

php

<?php
 
namespace App\Http\Controllers;

A cached autocomplete endpoint in Laravel

caching validation query-ranking

Intermediate 8 steps

typescript

interface UserAgentInfo {
  browser: { name: string; version: string };
  os: { name: string; version: string };
  device: 'mobile' | 'tablet' | 'desktop';

Parsing a user-agent string with ordered rules

regex parsing pattern-matching

Intermediate 9 steps

javascript

const express = require('express');
const router = express.Router();
const db = require('../db');

Building a paginated orders page in Express

pagination routing sql-queries

Intermediate 7 steps

go

package middleware
 
import (
	"context"

Per-tenant daily rate limiting in Gin

rate-limiting middleware redis

Intermediate 8 steps

java

public List<DailySample> backfillMissingDates(List<DailySample> samples, double fillValue) {
    if (samples.isEmpty()) {
        return List.of();
    }

Backfilling gaps in a daily time series in Java

streams time-series treemap

Intermediate 5 steps

rust

use axum::{
    extract::Query,
    response::IntoResponse,
    Json,

Parsing query strings in Axum handlers

deserialization query-parameters defaults

Intermediate 7 steps

javascript

import { Suspense } from 'react';
import { searchProducts } from '@/lib/products';
import SearchInput from './search-input';

Streaming search results in a Next.js Server Component

server-components suspense streaming

Intermediate 8 steps

php

<?php
 
declare(strict_types=1);

Normalizing human names in PHP

unicode text-normalization transliteration

Intermediate 8 steps

python

from functools import wraps
 
from flask import Blueprint, abort, jsonify
from flask_login import current_user, login_required

Building an admin-only decorator in Flask

decorators authorization access-control

Intermediate 7 steps

ruby

class BackfillUsersFullName < ActiveRecord::Migration[7.1]
  disable_ddl_transaction!
 
  BATCH_SIZE = 5_000

How to backfill a column safely in Rails

migrations batching backfill

Intermediate 7 steps

java

public final class Ulid {
 
    private static final char[] ENCODING = "0123456789ABCDEFGHJKMNPQRSTVWXYZ".toCharArray();
    private static final SecureRandom RANDOM = new SecureRandom();

How to generate a ULID in Java

base32-encoding bit-manipulation identifiers

Intermediate 8 steps

typescript

import { Injectable, inject } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { Observable, timer, throwError } from 'rxjs';
import { switchMap, takeWhile, filter, take, catchError } from 'rxjs/operators';

Polling a job until it finishes in Angular

rxjs polling observables

Intermediate 7 steps

javascript

import { useState } from 'react';
 
function StarRating({ value = 0, max = 5, onChange, size = 24 }) {
  const [hovered, setHovered] = useState(null);

Building an accessible star rating in React

controlled-component accessibility state-management

Intermediate 8 steps

rust

use std::borrow::Cow;
 
pub fn escape_html(input: &str) -> Cow<'_, str> {
    let needs_escape = input

Zero-copy HTML escaping with Cow in Rust

clone-on-write zero-copy string-escaping

Intermediate 6 steps

php

<?php
 
namespace App\Http\Controllers;

Handling Stripe webhooks in Laravel

webhooks signature-verification dependency-injection

Intermediate 7 steps

python

from django.urls import path, include
 
app_name = "api"

How URL-namespaced API versioning works in Django

api versioning url routing namespaces

Intermediate 8 steps

ruby

class ProjectsController < ApplicationController
  def new
    @project = current_account.projects.build
    load_form_collections

The new/create pattern in a Rails controller

mvc strong-parameters tenant-scoping

Intermediate 7 steps

java

@RestController
@RequestMapping("/api/reports")
public class ReportController {

Header-driven endpoints in a Spring controller

rest api request headers dependency injection

Intermediate 7 steps