Intermediate code explainers

typescript

import { Injectable, UnauthorizedException } from '@nestjs/common';
import { PassportStrategy } from '@nestjs/passport';
import { ExtractJwt, Strategy } from 'passport-jwt';
import { ConfigService } from '@nestjs/config';

How a JWT strategy authenticates in NestJS

authentication jwt passport

Intermediate 7 steps

rust

use std::cmp::Ordering;
 
pub struct PrefixIndex {
    entries: Vec<String>,

Prefix search with binary partitioning in Rust

binary-search sorting case-insensitive

Intermediate 7 steps

php

<?php
 
namespace App\Http\Controllers;

Streaming a filtered CSV export in Laravel

streaming csv-export query-builder

Intermediate 9 steps

javascript

const express = require('express');
const router = express.Router();
const { pool } = require('../db');
const redis = require('../redis');

Building a health check endpoint in Express

health-check timeouts promise-race

Intermediate 9 steps

ruby

class CreateOrderItems < ActiveRecord::Migration[7.1]
  def change
    create_table :order_items do |t|
      t.references :order, null: false, foreign_key: { on_delete: :cascade }

Enforcing order-item integrity in Rails

migrations foreign-keys validations

Intermediate 7 steps

java

public final class Slugifier {
 
    private static final Pattern NON_LATIN = Pattern.compile("[^\\w-]");
    private static final Pattern WHITESPACE = Pattern.compile("[\\s]+");

Building a URL slugifier in Java

regex unicode-normalization string-processing

Intermediate 8 steps

go

package auth
 
import (
	"net/http"

Setting and reading secure session cookies in Go

cookies session-management security

Intermediate 6 steps

rust

use std::cmp::Ordering;
use std::str::FromStr;
 
#[derive(Debug, Clone, PartialEq, Eq)]

Parsing and ordering semantic versions in Rust

parsing trait-implementation ordering

Intermediate 8 steps

javascript

'use client';
 
import { useEffect } from 'react';
import * as Sentry from '@sentry/nextjs';

How a Next.js error boundary recovers

error-boundary error-handling observability

Intermediate 8 steps

ruby

class Registration < ApplicationRecord
  belongs_to :event
 
  validates :email, presence: true, format: { with: URI::MailTo::EMAIL_REGEXP }

Validating registrations in Rails

validations i18n error-handling

Intermediate 8 steps

typescript

import { CanActivate, ExecutionContext, Injectable, UnauthorizedException } from '@nestjs/common';
import { GqlExecutionContext } from '@nestjs/graphql';
import { Reflector } from '@nestjs/core';
import { JwtService } from '@nestjs/jwt';

How a GraphQL auth guard works in NestJS

authentication authorization jwt

Intermediate 7 steps

python

import os
from datetime import timedelta

Class-based config in a Flask app factory

configuration app-factory inheritance

Intermediate 7 steps

typescript

type ResizeCallback = (size: { width: number; height: number }) => void;
 
export function observeResize(callback: ResizeCallback, delay = 150) {
  let timeoutId: ReturnType<typeof setTimeout> | undefined;

Debouncing window resize in TypeScript

debounce closures event-listeners

Intermediate 6 steps

ruby

class ApacheLogParser
  LINE_PATTERN = /\A(?<ip>\S+)\s\S+\s\S+\s\[(?<time>[^\]]+)\]\s"(?<method>[A-Z]+)\s(?<path>\S+)\s(?<protocol>[^"]+)"\s(?<status>\d{3})\s(?<bytes>\d+|-)/
 
  TIME_FORMAT = "%d/%b/%Y:%H:%M:%S %z"

Parsing Apache logs with named captures

regex named-captures parsing

Intermediate 6 steps

go

package middleware
 
import (
	"net/http"

A maintenance-mode gate in Gin

middleware atomic-flag concurrency

Intermediate 8 steps

php

<?php
 
namespace App\Services;

Batch image resizing with PHP GD

image-processing constructor-promotion match-expression

Intermediate 10 steps

java

public record FixedWidthField(String name, int start, int end) {
 
    public String extract(String line) {
        int from = Math.min(start, line.length());

Parsing fixed-width text in Java

records parsing streams

Intermediate 7 steps

javascript

const MAX_BATCH_SIZE = 20;
const FLUSH_INTERVAL = 5000;
const ENDPOINT = '/api/analytics';

Batching analytics events in the browser

batching buffering sendbeacon

Intermediate 10 steps