Code Explainers

Code explainers tagged #event-handling

javascript 
const STORAGE_KEY = "theme-preference";
 
function getSystemTheme() {
  return window.matchMedia("(prefers-color-scheme: dark)").matches

Building a dark-mode toggle that respects the OS

dark-mode localstorage matchmedia
Intermediate 8 steps
typescript 
import { Directive, EventEmitter, HostListener, Input, Output } from '@angular/core';
 
interface Shortcut {
  key: string;

A keyboard shortcut directive in Angular

directives event-handling keyboard-shortcuts
Intermediate 9 steps
typescript 
type Handler = (event: KeyboardEvent) => void;
 
interface Binding {
  combo: string;

Building a keyboard shortcut manager in TypeScript

event-handling normalization closures
Intermediate 7 steps
javascript 
class StarRating {
  constructor(container, { max = 5, value = 0, onChange } = {}) {
    this.container = container;
    this.max = max;

Building an accessible star-rating widget

dom event-handling accessibility
Intermediate 7 steps
typescript 
import {
  Controller,
  Post,
  Headers,

Verifying Stripe webhooks in NestJS

webhooks signature-verification event-handling
Intermediate 7 steps
typescript 
import { Processor, WorkerHost, OnWorkerEvent } from '@nestjs/bullmq';
import { Logger } from '@nestjs/common';
import { Job } from 'bullmq';
import { MailerService } from '../mailer/mailer.service';

Processing background email jobs in NestJS

job-queue background-processing dependency-injection
Intermediate 7 steps
javascript 
const express = require('express');
const Stripe = require('stripe');
 
const stripe = new Stripe(process.env.STRIPE_SECRET_KEY);

Verifying Stripe webhooks in Express

webhooks signature-verification raw-body
Intermediate 7 steps
typescript 
function throttle<T extends (...args: any[]) => void>(
  fn: T,
  limit: number
): (...args: Parameters<T>) => void {

Building a trailing-edge throttle in TypeScript

throttling closures generics
Intermediate 7 steps
java 
@RestController
@RequestMapping("/webhooks/stripe")
public class StripeWebhookController {
 

How a Stripe webhook controller works in Spring

webhooks signature-verification event-handling
Intermediate 7 steps