Intermediate code explainers

typescript

import { registerLocaleData } from '@angular/common';
import localeFr from '@angular/common/locales/fr';
import localeFrExtra from '@angular/common/locales/extra/fr';
import localeDe from '@angular/common/locales/de';

Locale-aware bootstrapping in Angular

i18n localization dependency-injection

Intermediate 8 steps

php

<?php
 
class NameParser
{

Parsing a full name into components in PHP

string-parsing arrays normalization

Intermediate 8 steps

rust

use serde::Deserialize;
 
#[derive(Debug, Deserialize)]
#[serde(untagged)]

Parsing flexible JSON shapes with serde

deserialization enums json

Intermediate 6 steps

ruby

require "shellwords"
require "open3"
 
module Backup

Building safe shell commands in Ruby

shell-out subprocess command-injection

Intermediate 7 steps

python

from fastapi import FastAPI, WebSocket, WebSocketDisconnect
 
app = FastAPI()

Building a WebSocket chat with FastAPI

websockets broadcast connection-management

Intermediate 9 steps

typescript

import { Module } from '@nestjs/common';
import { ConfigModule } from '@nestjs/config';
import * as Joi from 'joi';

Validating env config at boot in NestJS

configuration schema-validation environment-variables

Intermediate 8 steps

php

<?php
 
namespace App\Services\Checkout;

Validating coupons with Laravel's Pipeline

pipeline chain of responsibility transactions

Intermediate 7 steps

rust

use std::cmp::{Ordering, Reverse};
use std::collections::BinaryHeap;
use std::fs::File;
use std::io::{self, BufRead, BufReader, BufWriter, Lines, Write};

K-way merge of sorted logs in Rust

binary-heap k-way-merge streaming-io

Intermediate 8 steps

ruby

class UserAgentParser
  BROWSERS = [
    [/Edg\/([\d.]+)/, "Edge"],
    [/OPR\/([\d.]+)/, "Opera"],

Parsing user-agent strings in Ruby

regex pattern-matching lookup-tables

Intermediate 8 steps

python

import time
import uuid
 
from django.utils.deprecation import MiddlewareMixin

Attaching per-request context in Django

middleware request lifecycle multi-tenancy

Intermediate 7 steps

javascript

function evaluate(expression) {
  const tokens = tokenize(expression);
  let pos = 0;

Building a recursive descent calculator

parsing recursion operator-precedence

Intermediate 8 steps

go

package api
 
import (
	"crypto/sha256"

ETag conditional requests in Gin

http-caching etag conditional-requests

Intermediate 6 steps

typescript

import { Inject, Injectable, Logger } from '@nestjs/common';
import { CACHE_MANAGER } from '@nestjs/cache-manager';
import { Cache } from 'cache-manager';
import { InjectRepository } from '@nestjs/typeorm';

A cache-aside country lookup in NestJS

cache-aside dependency-injection batch-lookup

Intermediate 8 steps

php

<?php
 
namespace App\Services;

How a password strength validator works in PHP

validation regular-expressions data-driven

Intermediate 8 steps

ruby

class LogAggregator
  BUCKET_FORMAT = "%Y-%m-%dT%H:%M"
 
  def initialize(entries)

Bucketing log entries by the minute in Ruby

aggregation hashing enumerable

Intermediate 5 steps

rust

use std::f64::consts::PI;
 
#[derive(Debug, Clone, Copy)]
pub struct LatLng {

Building geographic bounding boxes in Rust

geospatial value-types option

Intermediate 7 steps

java

package com.acme.billing.config;
 
import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
import org.springframework.boot.context.properties.ConfigurationProperties;

Feature-flagged beans with Spring @ConditionalOnProperty

feature-flags conditional-beans strategy-pattern

Intermediate 5 steps

typescript

import { Injectable, effect, signal, computed } from '@angular/core';
 
interface Preferences {
  theme: 'light' | 'dark';

A signal-based preferences store in Angular

signals state-management persistence

Intermediate 7 steps