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best-practices
Apply modern web development best practices for security, compatibility, and code quality. Use when asked to "apply best practices", "security audit", "modernize code", "code quality review", or "check for vulnerabilities".
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Apply modern web development best practices for security, compatibility, and code quality. Use when asked to "apply best practices", "security audit", "modernize code", "code quality review", or "check for vulnerabilities".
Gera 10 conceitos criativos de PERFORMANCE para Meta Ads (Facebook/Instagram) usando framework Hook → Hold → Offer e 40+ Creative Types com mapeamento de emoção e estágio de funil. Cada conceito inclui estratégia direct response, copy com limites de caracteres, conceito visual funcional, variações A/B de hook, prompt de imagem e adaptações por placement. Orientado por design system — quando não fornecido, EXTRAI automaticamente de referências visuais do cliente. Sem design system = SLOP. Use quando precisar criar anúncios de conversão para Instagram ou Facebook, gerar conceitos criativos de performance para Meta Ads, criar peças direct response para feed, stories ou reels, desenvolver campanhas de lead generation ou vendas no Meta, ou qualquer variação de "criativos para Meta", "anúncios para Instagram", "campanha Facebook Ads", "peças para feed", "criativos de performance".
Expert in building 3D experiences for the web - Three.js, React Three Fiber, Spline, WebGL, and interactive 3D scenes. Covers product configurators, 3D portfolios, immersive websites, and bringing depth to web experiences. Use when: 3D website, three.js, WebGL, react three fiber, 3D experience.
Use when designing or implementing product-grade web motion like Stripe, Linear, Apple, and Vercel. Covers motion principles, easing/duration defaults, choreography patterns, scroll/hover interactions, performance, accessibility (reduced motion), and implementation guidance.
Comprehensive skill for Anime.js v4 - a fast and flexible JavaScript animation library. This skill should be used when implementing web animations, creating timelines, working with SVG animations, scroll-based animations, draggable elements, staggered effects, or any JavaScript-based animation on the web. Triggers on: "anime.js", "animejs", "animate elements", "CSS animation with JS", "timeline animation", "stagger animation", "SVG morphing", "motion path", "scroll animation", "draggable", "spring animation", "keyframe animation".
Expert AWS Cloud Advisor for architecture design, security review, and implementation guidance. Leverages AWS MCP tools for accurate, documentation-backed answers. Use when user asks about AWS architecture, security, service selection, migrations, troubleshooting, or learning AWS. Triggers on AWS, Lambda, S3, EC2, ECS, EKS, DynamoDB, RDS, CloudFormation, CDK, Terraform, Serverless, SAM, IAM, VPC, API Gateway, or any AWS service.
Deploy applications and infrastructure to Cloudflare using Workers, Pages, and related platform services. Use when the user asks to deploy, host, publish, or set up a project on Cloudflare.
| name | best-practices |
| description | Apply modern web development best practices for security, compatibility, and code quality. Use when asked to "apply best practices", "security audit", "modernize code", "code quality review", or "check for vulnerabilities". |
| license | MIT |
| metadata | {"author":"web-quality-skills","version":"1.0"} |
| version | 1.0.0 |
| updated | 2026-03-17 |
Modern web development standards based on Lighthouse best practices audits. Covers security, browser compatibility, and code quality patterns.
Enforce HTTPS:
<!-- ❌ Mixed content -->
<img src="http://example.com/image.jpg" />
<script src="http://cdn.example.com/script.js"></script>
<!-- ✅ HTTPS only -->
<img src="https://example.com/image.jpg" />
<script src="https://cdn.example.com/script.js"></script>
<!-- ✅ Protocol-relative (will use page's protocol) -->
<img src="//example.com/image.jpg" />
HSTS Header:
Strict-Transport-Security: max-age=31536000; includeSubDomains; preload
<!-- Basic CSP via meta tag -->
<meta
http-equiv="Content-Security-Policy"
content="default-src 'self';
script-src 'self' https://trusted-cdn.com;
style-src 'self' 'unsafe-inline';
img-src 'self' data: https:;
connect-src 'self' https://api.example.com;"
/>
<!-- Better: HTTP header -->
CSP Header (recommended):
Content-Security-Policy:
default-src 'self';
script-src 'self' 'nonce-abc123' https://trusted.com;
style-src 'self' 'nonce-abc123';
img-src 'self' data: https:;
connect-src 'self' https://api.example.com;
frame-ancestors 'self';
base-uri 'self';
form-action 'self';
Using nonces for inline scripts:
<script nonce="abc123">
// This inline script is allowed
</script>
# Prevent clickjacking
X-Frame-Options: DENY
# Prevent MIME type sniffing
X-Content-Type-Options: nosniff
# Enable XSS filter (legacy browsers)
X-XSS-Protection: 1; mode=block
# Control referrer information
Referrer-Policy: strict-origin-when-cross-origin
# Permissions policy (formerly Feature-Policy)
Permissions-Policy: geolocation=(), microphone=(), camera=()
# Check for vulnerabilities
npm audit
yarn audit
# Auto-fix when possible
npm audit fix
# Check specific package
npm ls lodash
Keep dependencies updated:
// package.json
{
"scripts": {
"audit": "npm audit --audit-level=moderate",
"update": "npm update && npm audit fix"
}
}
Known vulnerable patterns to avoid:
// ❌ Prototype pollution vulnerable patterns
Object.assign(target, userInput)
_.merge(target, userInput)
// ✅ Safer alternatives
const safeData = JSON.parse(JSON.stringify(userInput))
// ❌ XSS vulnerable
element.innerHTML = userInput
document.write(userInput)
// ✅ Safe text content
element.textContent = userInput
// ✅ If HTML needed, sanitize
import DOMPurify from 'dompurify'
element.innerHTML = DOMPurify.sanitize(userInput)
// ❌ Insecure cookie
document.cookie = "session=abc123";
// ✅ Secure cookie (server-side)
Set-Cookie: session=abc123; Secure; HttpOnly; SameSite=Strict; Path=/
<!-- ❌ Missing or invalid doctype -->
<html>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN">
<!-- ✅ HTML5 doctype -->
<!DOCTYPE html>
<html lang="en"></html>
</html>
<!-- ❌ Missing or late charset -->
<html>
<head>
<title>Page</title>
<meta charset="UTF-8" />
</head>
<!-- ✅ Charset as first element in head -->
<html>
<head>
<meta charset="UTF-8" />
<title>Page</title>
</head>
</html>
</html>
<!-- ❌ Missing viewport -->
<head>
<title>Page</title>
</head>
<!-- ✅ Responsive viewport -->
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1" />
<title>Page</title>
</head>
// ❌ Browser detection (brittle)
if (navigator.userAgent.includes('Chrome')) {
// Chrome-specific code
}
// ✅ Feature detection
if ('IntersectionObserver' in window) {
// Use IntersectionObserver
} else {
// Fallback
}
// ✅ Using @supports in CSS
@supports (display: grid) {
.container {
display: grid;
}
}
@supports not (display: grid) {
.container {
display: flex;
}
}
<!-- Load polyfills conditionally -->
<script>
if (!('fetch' in window)) {
document.write('<script src="/polyfills/fetch.js"><\/script>')
}
</script>
<!-- Or use polyfill.io -->
<script src="https://polyfill.io/v3/polyfill.min.js?features=fetch,IntersectionObserver"></script>
// ❌ document.write (blocks parsing)
document.write('<script src="..."></script>');
// ✅ Dynamic script loading
const script = document.createElement('script');
script.src = '...';
document.head.appendChild(script);
// ❌ Synchronous XHR (blocks main thread)
const xhr = new XMLHttpRequest();
xhr.open('GET', url, false); // false = synchronous
// ✅ Async fetch
const response = await fetch(url);
// ❌ Application Cache (deprecated)
<html manifest="cache.manifest">
// ✅ Service Workers
if ('serviceWorker' in navigator) {
navigator.serviceWorker.register('/sw.js');
}
// ❌ Non-passive touch/wheel (may block scrolling)
element.addEventListener('touchstart', handler)
element.addEventListener('wheel', handler)
// ✅ Passive listeners (allows smooth scrolling)
element.addEventListener('touchstart', handler, { passive: true })
element.addEventListener('wheel', handler, { passive: true })
// ✅ If you need preventDefault, be explicit
element.addEventListener('touchstart', handler, { passive: false })
// ❌ Errors in production
console.log('Debug info') // Remove in production
throw new Error('Unhandled') // Catch all errors
// ✅ Proper error handling
try {
riskyOperation()
} catch (error) {
// Log to error tracking service
errorTracker.captureException(error)
// Show user-friendly message
showErrorMessage('Something went wrong. Please try again.')
}
class ErrorBoundary extends React.Component {
state = { hasError: false }
static getDerivedStateFromError(error) {
return { hasError: true }
}
componentDidCatch(error, info) {
errorTracker.captureException(error, { extra: info })
}
render() {
if (this.state.hasError) {
return <FallbackUI />
}
return this.props.children
}
}
// Usage
;<ErrorBoundary>
<App />
</ErrorBoundary>
// Catch unhandled errors
window.addEventListener('error', (event) => {
errorTracker.captureException(event.error)
})
// Catch unhandled promise rejections
window.addEventListener('unhandledrejection', (event) => {
errorTracker.captureException(event.reason)
})
// ❌ Source maps exposed in production
// webpack.config.js
module.exports = {
devtool: 'source-map', // Exposes source code
}
// ✅ Hidden source maps (uploaded to error tracker)
module.exports = {
devtool: 'hidden-source-map',
}
// ✅ Or no source maps in production
module.exports = {
devtool: process.env.NODE_ENV === 'production' ? false : 'source-map',
}
// ❌ Blocking script
<script src="heavy-library.js"></script>
// ✅ Deferred script
<script defer src="heavy-library.js"></script>
// ❌ Blocking CSS import
@import url('other-styles.css');
// ✅ Link tags (parallel loading)
<link rel="stylesheet" href="styles.css">
<link rel="stylesheet" href="other-styles.css">
// ❌ Handler on every element
items.forEach((item) => {
item.addEventListener('click', handleClick)
})
// ✅ Event delegation
container.addEventListener('click', (e) => {
if (e.target.matches('.item')) {
handleClick(e)
}
})
// ❌ Memory leak (never removed)
const handler = () => {
/* ... */
}
window.addEventListener('resize', handler)
// ✅ Cleanup when done
const handler = () => {
/* ... */
}
window.addEventListener('resize', handler)
// Later, when component unmounts:
window.removeEventListener('resize', handler)
// ✅ Using AbortController
const controller = new AbortController()
window.addEventListener('resize', handler, { signal: controller.signal })
// Cleanup:
controller.abort()
<!-- ❌ Invalid HTML -->
<div id="header">
<div id="header">
<!-- Duplicate ID -->
<ul>
<div>Item</div>
<!-- Invalid child -->
</ul>
<a href="/"><button>Click</button></a>
<!-- Invalid nesting -->
<!-- ✅ Valid HTML -->
<header id="site-header"></header>
<ul>
<li>Item</li>
</ul>
<a href="/" class="button">Click</a>
</div>
</div>
<!-- ❌ Non-semantic -->
<div class="header">
<div class="nav">
<div class="nav-item">Home</div>
</div>
</div>
<div class="main">
<div class="article">
<div class="title">Headline</div>
</div>
</div>
<!-- ✅ Semantic HTML5 -->
<header>
<nav>
<a href="/">Home</a>
</nav>
</header>
<main>
<article>
<h1>Headline</h1>
</article>
</main>
<!-- ❌ Distorted images -->
<img src="photo.jpg" width="300" height="100" />
<!-- If actual ratio is 4:3, this squishes the image -->
<!-- ✅ Preserve aspect ratio -->
<img src="photo.jpg" width="300" height="225" />
<!-- Actual 4:3 dimensions -->
<!-- ✅ CSS object-fit for flexibility -->
<img src="photo.jpg" style="width: 300px; height: 200px; object-fit: cover;" />
// ❌ Request on page load (bad UX, often denied)
navigator.geolocation.getCurrentPosition(success, error)
// ✅ Request in context, after user action
findNearbyButton.addEventListener('click', async () => {
// Explain why you need it
if (await showPermissionExplanation()) {
navigator.geolocation.getCurrentPosition(success, error)
}
})
<!-- Restrict powerful features -->
<meta http-equiv="Permissions-Policy" content="geolocation=(), camera=(), microphone=()" />
<!-- Or allow for specific origins -->
<meta http-equiv="Permissions-Policy" content="geolocation=(self 'https://maps.example.com')" />
npm audit)| Tool | Purpose |
|---|---|
npm audit | Dependency vulnerabilities |
| SecurityHeaders.com | Header analysis |
| W3C Validator | HTML validation |
| Lighthouse | Best practices audit |
| Observatory | Security scan |