Intermediate code explainers

rust

use axum::body::Bytes;
use axum::http::{header, HeaderValue, StatusCode};
use axum::response::{IntoResponse, Response};
use serde::Serialize;

Custom Axum responses with per-user ETags

etag trait-implementation generics

Intermediate 7 steps

python

import base64
import json
from typing import Annotated, Optional

Cursor pagination in a FastAPI endpoint

pagination cursor async

Intermediate 9 steps

javascript

class LyricsSync {
  constructor(audio, container, lines) {
    this.audio = audio;
    this.container = container;

Building a synced lyrics highlighter

binary-search dom-manipulation event-handling

Intermediate 9 steps

typescript

import { Body, Controller, Ip, Post, UnauthorizedException } from '@nestjs/common';
import { Throttle, ThrottlerGuard } from '@nestjs/throttler';
import { UseGuards } from '@nestjs/common';
import { AuthService } from './auth.service';

Rate-limiting an auth flow in NestJS

rate-limiting authentication guards

Intermediate 8 steps

java

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

Validating query params in a Spring controller

validation pagination rest-api

Intermediate 8 steps

php

<?php
 
namespace App\Services;

Merging overlapping busy time blocks in PHP

interval-merging sorting datetime

Intermediate 8 steps

rust

use axum::{extract::State, http::StatusCode, response::IntoResponse, Json};
use serde::{Deserialize, Serialize};
use std::sync::Arc;

Batch inserts with per-item status in Axum

batch-processing error-handling serde

Intermediate 8 steps

typescript

import { Component, computed, DestroyRef, inject, input, output, signal } from '@angular/core';
import { takeUntilDestroyed } from '@angular/core/rxjs-interop';
import { interval, map, takeWhile } from 'rxjs';

How a signal-driven countdown works in Angular

signals reactivity rxjs

Intermediate 8 steps

php

<?php
 
namespace App\Listeners;

How event subscribers group listeners in Laravel

event-driven subscribers queues

Intermediate 6 steps

javascript

const express = require('express');
 
const app = express();

Enforcing HTTPS with Express middleware

middleware https security

Intermediate 6 steps

rust

use std::time::Duration;
 
#[derive(Debug, PartialEq)]
pub enum ParseDurationError {

Parsing duration strings safely in Rust

parsing error-handling checked-arithmetic

Intermediate 8 steps

java

@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Constraint(validatedBy = PasswordsMatchValidator.class)
public @interface PasswordsMatch {

Custom cross-field validation in Spring

bean-validation custom-constraints cross-field-validation

Intermediate 8 steps

go

package logparse
 
import (
	"bufio"

Splitting multi-line logs with a Scanner

parsing streaming bufio

Intermediate 9 steps

typescript

type TokenType = "keyword" | "string" | "comment" | "number" | "text";
 
interface Token {
  type: TokenType;

How a regex tokenizer highlights code

tokenizer regex lexing

Intermediate 10 steps

ruby

module Rack
  class MaintenanceMode
    RETRY_AFTER = 3600

A Rack maintenance-mode middleware in Rails

middleware rack http-status

Intermediate 8 steps

php

<?php
 
namespace App\Services;

How user impersonation works in Laravel

authentication authorization session

Intermediate 8 steps

javascript

const express = require('express');
const router = express.Router();
 
router.get('/articles/:slug', async (req, res, next) => {

Conditional GET caching in Express

http-caching conditional-get routing

Intermediate 8 steps

rust

use std::time::Duration;
 
#[derive(Debug, Clone, Copy)]
pub struct LatencyStats {

Computing latency percentiles in Rust

percentiles interpolation closures

Intermediate 6 steps