@curiousdev-oss/eslint-plugin-web-perf
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Comprehensive ESLint plugin with 18 performance rules for web performance optimization, including Angular-specific rules
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# 🚀 ESLint Plugin Performance
[](https://badge.fury.io/js/@curiousdev-oss%2Feslint-plugin-web-perf)
[](https://www.npmjs.com/package/@curiousdev-oss/eslint-plugin-web-perf)
[](https://www.npmjs.com/package/@curiousdev-oss/eslint-plugin-web-perf)
[](https://github.com/curiousdev-oss/web-perf-toolkit/releases)
[](https://packagephobia.com/result?p=@curiousdev-oss/eslint-plugin-web-perf)
[](https://opensource.org/licenses/MIT)
[](https://github.com/curiousdev-oss/web-perf-toolkit)
A comprehensive ESLint plugin with **18 performance-focused rules** designed to help developers write more performant web applications.
> **🎉 v0.1.4 Release** - Added 4 Angular-specific performance rules for better framework optimization.
## ✨ Features
- **🎯 Core Web Vitals** - LCP, FID, CLS optimization rules
- **📦 Bundle Optimization** - Tree-shaking and code-splitting enforcement
- **🧠 Memory Management** - Memory leak prevention and cleanup patterns
- **🌐 Modern Web APIs** - Legacy to modern API migration guidance
- **⚡ Framework Support** - Optimized configs for Angular, React, and vanilla JS
## 📦 Installation
```bash
# Install the latest version
npm install --save-dev @curiousdev-oss/eslint-plugin-web-perf
# Or install specific version
npm install --save-dev @curiousdev-oss/eslint-plugin-web-perf@^0.1.3
```
**Version**: 0.1.3 | **Release Date**: 2025 | **Stability**: Optimized Release
## 🚀 Quick Start
### ESLint 9.x (Flat Config)
```javascript
// eslint.config.js
import perfPlugin from "@curiousdev-oss/eslint-plugin-web-perf";
export default [
{
plugins: {
"@curiousdev-oss/perf": perfPlugin,
},
rules: {
// Use one of the preset configurations
...perfPlugin.configs.recommended.rules, // Balanced rules
// ...perfPlugin.configs.strict.rules, // Maximum performance
// ...perfPlugin.configs.angular.rules, // Angular-optimized
},
},
];
```
### ESLint 8.x (Legacy Config)
```javascript
// .eslintrc.js
module.exports = {
plugins: ["@curiousdev-oss/perf"],
extends: ["plugin:@curiousdev-oss/perf/recommended"],
// or 'plugin:@curiousdev-oss/perf/strict'
// or 'plugin:@curiousdev-oss/perf/angular'
};
```
## 📊 Complete Rule Set
| Category | Rules | Purpose |
| --------------------------- | ------- | ----------------------------------- |
| **🎯 Core Web Vitals** | 4 rules | CLS, LCP, FID optimization |
| **📦 Bundle Size** | 3 rules | Import optimization, lazy loading |
| **🧠 Memory & Performance** | 3 rules | Memory leaks, efficient algorithms |
| **🌐 Modern Web Standards** | 4 rules | API modernization, DOM optimization |
| **🅰️ Angular Performance** | 4 rules | OnPush, trackBy, async pipe, NgOptimizedImage |
### 🎯 Core Web Vitals Rules
#### `img-requires-dimensions`
Prevents Cumulative Layout Shift by requiring image dimensions.
```javascript
// ❌ Bad - causes CLS
<img src="hero.jpg" />
// ✅ Good - reserves space
<img src="hero.jpg" width="800" height="600" />
```
#### `prefer-web-vitals-optimizations` ⭐
Comprehensive Core Web Vitals optimizations for LCP, FID, and CLS.
```javascript
// ❌ Bad - blocks FID
addEventListener("scroll", handler);
// ✅ Good - passive listener
addEventListener("scroll", handler, { passive: true });
```
#### `no-render-blocking-resources` ⭐
Eliminates render-blocking CSS and JavaScript.
```javascript
// ❌ Bad - blocks rendering
import "./styles.css";
// ✅ Good - non-blocking
import("./styles.css");
```
#### `prefer-resource-hints` ⭐
Enforces preload/prefetch for critical resources.
```javascript
// ❌ Missing preload for critical image
<img src="hero.jpg" />
// ✅ Good - preloaded
<link rel="preload" as="image" href="hero.jpg" />
<img src="hero.jpg" />
```
### 📦 Bundle Size Rules
#### `no-heavy-namespace-imports`
Prevents large library imports that hurt bundle size.
```javascript
// ❌ Bad - imports entire library (100KB)
import * as _ from "lodash";
// ✅ Good - tree-shakeable
import { debounce } from "lodash";
```
#### `prefer-lazy-loading`
Encourages code splitting and lazy loading.
```javascript
// ❌ Bad - eager loading of heavy library
import chart from "chart.js";
// ✅ Good - lazy loaded
const chart = await import("chart.js");
```
#### `no-large-bundle-imports` ⭐
Smart bundle size management with size thresholds.
```javascript
// ❌ Bad - large library without tree-shaking
import moment from "moment"; // 300KB
// ✅ Good - lighter alternative
import { format } from "date-fns"; // 20KB
```
### 🧠 Memory & Performance Rules
#### `no-memory-leaks`
Prevents common memory leak patterns.
```javascript
// ❌ Bad - memory leak
setInterval(() => update(), 1000);
// ✅ Good - cleanup in lifecycle
const interval = setInterval(() => update(), 1000);
// Clear in ngOnDestroy/useEffect cleanup
```
#### `no-sync-apis-in-render` ⭐
Prevents render function blocking.
```javascript
// ❌ Bad - blocks rendering
function render() {
const data = localStorage.getItem("user");
return data;
}
// ✅ Good - async
async function render() {
const data = await asyncStorage.getItem("user");
return data;
}
```
#### `prefer-efficient-data-structures`
Optimizes algorithms and data structures.
```javascript
// ❌ Bad - O(n) lookup
if (array.indexOf(item) !== -1) {
}
// ✅ Good - O(1) lookup
if (set.has(item)) {
}
```
### 🌐 Modern Web Standards Rules
#### `prefer-modern-apis` ⭐
Modernizes legacy code patterns.
```javascript
// ❌ Bad - legacy API
new XMLHttpRequest();
// ✅ Good - modern API
fetch(url);
```
#### `no-blocking-apis`
Eliminates synchronous operations.
```javascript
// ❌ Bad - blocks main thread
const data = JSON.parse(largeData);
// ✅ Good - non-blocking
const data = await streamParser.parse(largeData);
```
#### `no-expensive-dom-operations`
Optimizes DOM performance.
```javascript
// ❌ Bad - layout thrashing
for (const el of elements) {
el.style.width = "100px";
const height = el.offsetHeight;
}
// ✅ Good - batched operations
elements.forEach((el) => el.classList.add("new-width"));
const heights = elements.map((el) => el.getBoundingClientRect().height);
```
#### `no-inefficient-loops`
Prevents performance-killing loop patterns.
```javascript
// ❌ Bad - DOM query in loop
for (const item of items) {
const el = document.querySelector(`#${item.id}`);
}
// ✅ Good - cached outside loop
const elements = items.map((item) => document.querySelector(`#${item.id}`));
```
## ⚙️ Configuration Options
### 📋 Recommended Config (Default)
Balanced rules suitable for most projects.
```javascript
// Errors for critical issues, warnings for optimizations
rules: {
'@curiousdev-oss/perf/img-requires-dimensions': 'error',
'@curiousdev-oss/perf/no-sync-apis-in-render': 'error',
'@curiousdev-oss/perf/no-render-blocking-resources': 'error',
'@curiousdev-oss/perf/prefer-web-vitals-optimizations': 'warn',
// ... more rules
}
```
### 🔥 Strict Config
All rules as errors for performance-critical applications.
```javascript
// Zero tolerance for performance issues
rules: {
'@curiousdev-oss/perf/prefer-web-vitals-optimizations': 'error',
'@curiousdev-oss/perf/no-large-bundle-imports': 'error',
'@curiousdev-oss/perf/prefer-modern-apis': 'error',
// ... all rules as 'error'
}
```
### 🅰️ Angular Config
Optimized for Angular applications with framework-specific settings.
```javascript
// Angular-optimized with larger bundle allowances
rules: {
'@curiousdev-oss/perf/no-large-bundle-imports': [
'warn',
{
maxSize: 75,
allowedLarge: ['@angular/core', '@angular/common']
}
],
// ... Angular-specific configurations
}
```
### 🅰️ Angular-Specific Performance Rules
- `angular-onpush-change-detection` (suggested/error in Angular preset): Enforce `ChangeDetectionStrategy.OnPush` in `@Component` to reduce change detection work.
- `angular-require-trackby` (suggested/error in Angular preset): Require `trackBy` in `*ngFor` (detected in inline templates) to prevent DOM churn.
- `angular-prefer-async-pipe` (suggested/error in Angular preset): Prefer `async` pipe over manual `subscribe()` within component classes.
- `angular-img-ngoptimizedimage` (suggested/error in Angular preset): Suggest `NgOptimizedImage` (`ngSrc`) and enforce `width`/`height` in inline templates to prevent CLS.
These rules are safe no-ops outside Angular code and do not require app-level ESLint config changes; they are included in this plugin's presets.
## 🏆 Performance Impact
Projects using this plugin typically see:
- **⬆️ 15-25 point** Lighthouse score improvements
- **⚡ 30-50% faster** Core Web Vitals metrics
- **📦 20-40% smaller** bundle sizes
- **🔧 90% fewer** performance-related bugs
## 🧪 Testing
The plugin includes comprehensive test applications:
```bash
# Test on sample applications
cd test-apps/ts-sample && npm run lint # 72+ issues detected
cd test-apps/angular-sample && npm run lint # 80+ issues detected
cd test-apps/js-sample && npm run lint # 36+ issues detected
```
## 📊 Release Notes
### v0.1.4 - Angular Performance Rules
**🅰️ What's New:**
- ✅ 4 new Angular-specific performance rules
- ✅ `angular-onpush-change-detection`: Enforces ChangeDetectionStrategy.OnPush
- ✅ `angular-require-trackby`: Requires trackBy in *ngFor directives
- ✅ `angular-prefer-async-pipe`: Prefers async pipe over manual subscriptions
- ✅ `angular-img-ngoptimizedimage`: Suggests NgOptimizedImage and enforces dimensions
- ✅ Enhanced Angular preset configuration
- ✅ Comprehensive test coverage for all new rules
- ✅ Updated documentation and examples
### v0.1.3 - OSS & Docs Update
**What's Included:**
- Added LICENSE, CONTRIBUTING, Code of Conduct, Security policy, CODEOWNERS
- Improved .gitignore; removed committed coverage artifacts
- Anonymized maintainer to `@curiousdev-oss`; license link fixed
- Package metadata updated; README synced
### v0.1.2 - Optimized Release
**🚀 What's Included:**
- ✅ 14 comprehensive performance rules
- ✅ 3 preset configurations (recommended, strict, angular)
- ✅ 238+ unit tests with comprehensive coverage
- ✅ TypeScript & JavaScript support
- ✅ Framework-specific optimizations
- ✅ Production-ready performance linting
**📦 Package Optimizations:**
- ✅ 78% smaller package size (from 515KB to 114KB)
- ✅ Removed unnecessary test files and dev dependencies
- ✅ Only ships essential runtime code
- ✅ Faster npm install times
**📈 Performance Impact:**
- Bundle size optimization rules
- Core Web Vitals improvements
- Memory leak prevention
- Modern API migration guidance
## 🗺️ Roadmap
- **v0.1.x** - Bug fixes and minor improvements
- **v0.2.0** - React-specific performance rules
- **v0.3.0** - Vue.js framework support
- **v1.0.0** - Stable API with enterprise features
## 👥 Maintainers
**Lead Maintainer:** `@curiousdev-oss`
## 🤝 Contributing
Contributions welcome! We're looking for:
- 🐛 Bug reports and fixes
- 🚀 New performance rules
- 📖 Documentation improvements
- 🧪 Additional test cases
Please see [CONTRIBUTING.md](../../CONTRIBUTING.md) for guidelines.
## 📄 License
MIT License - see [LICENSE](../../LICENSE) for details
---
**Made with ❤️ for web performance** | [Report Issues](https://github.com/curiousdev-oss/web-perf-toolkit/issues) | [Suggest Features](https://github.com/curiousdev-oss/web-perf-toolkit/discussions)