第84天：性能优化综合实践

学习目标

• 掌握 Element Plus 应用的全面性能优化策略
• 学习性能监控和分析工具的使用
• 实现从开发到生产的性能优化最佳实践
• 构建高性能的企业级应用

1. 性能优化策略体系

1.1 性能优化管理器

// 性能优化管理器
class PerformanceOptimizationManager {
  private metrics: Map<string, PerformanceMetric> = new Map()
  private optimizations: Map<string, OptimizationStrategy> = new Map()
  private observers: PerformanceObserver[] = []
  
  constructor() {
    this.initializeOptimizations()
    this.setupPerformanceObservers()
  }
  
  // 初始化优化策略
  private initializeOptimizations(): void {
    // 加载优化
    this.optimizations.set('loading', {
      name: '加载优化',
      strategies: [
        '代码分割',
        '懒加载',
        '预加载',
        '缓存策略',
        '资源压缩'
      ],
      priority: 'high',
      impact: 'high'
    })
    
    // 渲染优化
    this.optimizations.set('rendering', {
      name: '渲染优化',
      strategies: [
        '虚拟滚动',
        '组件缓存',
        'DOM优化',
        '重绘重排优化',
        '动画优化'
      ],
      priority: 'high',
      impact: 'medium'
    })
    
    // 内存优化
    this.optimizations.set('memory', {
      name: '内存优化',
      strategies: [
        '内存泄漏检测',
        '对象池',
        '垃圾回收优化',
        '事件监听器清理',
        '组件销毁优化'
      ],
      priority: 'medium',
      impact: 'high'
    })
    
    // 网络优化
    this.optimizations.set('network', {
      name: '网络优化',
      strategies: [
        'HTTP/2',
        'CDN',
        '请求合并',
        '数据缓存',
        '离线策略'
      ],
      priority: 'medium',
      impact: 'medium'
    })
  }
  
  // 设置性能观察器
  private setupPerformanceObservers(): void {
    // 导航性能观察器
    const navigationObserver = new PerformanceObserver((list) => {
      for (const entry of list.getEntries()) {
        this.recordMetric('navigation', {
          name: entry.name,
          duration: entry.duration,
          startTime: entry.startTime,
          type: entry.entryType
        })
      }
    })
    
    navigationObserver.observe({ entryTypes: ['navigation'] })
    this.observers.push(navigationObserver)
    
    // 资源加载观察器
    const resourceObserver = new PerformanceObserver((list) => {
      for (const entry of list.getEntries()) {
        this.recordMetric('resource', {
          name: entry.name,
          duration: entry.duration,
          transferSize: (entry as PerformanceResourceTiming).transferSize,
          type: entry.entryType
        })
      }
    })
    
    resourceObserver.observe({ entryTypes: ['resource'] })
    this.observers.push(resourceObserver)
    
    // 长任务观察器
    if ('PerformanceObserver' in window && 'longtask' in PerformanceObserver.supportedEntryTypes) {
      const longTaskObserver = new PerformanceObserver((list) => {
        for (const entry of list.getEntries()) {
          this.recordMetric('longtask', {
            name: entry.name,
            duration: entry.duration,
            startTime: entry.startTime,
            type: entry.entryType
          })
        }
      })
      
      longTaskObserver.observe({ entryTypes: ['longtask'] })
      this.observers.push(longTaskObserver)
    }
  }
  
  // 记录性能指标
  private recordMetric(category: string, metric: any): void {
    const key = `${category}-${Date.now()}`
    this.metrics.set(key, {
      category,
      timestamp: Date.now(),
      data: metric
    })
    
    // 限制指标数量
    if (this.metrics.size > 1000) {
      const oldestKey = this.metrics.keys().next().value
      this.metrics.delete(oldestKey)
    }
  }
  
  // 分析性能瓶颈
  analyzeBottlenecks(): PerformanceAnalysis {
    const analysis: PerformanceAnalysis = {
      loadingIssues: this.analyzeLoadingIssues(),
      renderingIssues: this.analyzeRenderingIssues(),
      memoryIssues: this.analyzeMemoryIssues(),
      networkIssues: this.analyzeNetworkIssues(),
      recommendations: []
    }
    
    analysis.recommendations = this.generateRecommendations(analysis)
    return analysis
  }
  
  // 分析加载问题
  private analyzeLoadingIssues(): LoadingIssue[] {
    const issues: LoadingIssue[] = []
    const navigationMetrics = Array.from(this.metrics.values())
      .filter(m => m.category === 'navigation')
    
    navigationMetrics.forEach(metric => {
      const data = metric.data as PerformanceNavigationTiming
      
      // 检查首屏时间
      const fcp = data.duration
      if (fcp > 2000) {
        issues.push({
          type: 'slow-fcp',
          severity: 'high',
          description: `首屏渲染时间过长: ${fcp}ms`,
          suggestion: '考虑代码分割和资源优化'
        })
      }
      
      // 检查DNS解析时间
      const dnsTime = data.domainLookupEnd - data.domainLookupStart
      if (dnsTime > 100) {
        issues.push({
          type: 'slow-dns',
          severity: 'medium',
          description: `DNS解析时间过长: ${dnsTime}ms`,
          suggestion: '考虑使用DNS预解析或CDN'
        })
      }
    })
    
    return issues
  }
  
  // 分析渲染问题
  private analyzeRenderingIssues(): RenderingIssue[] {
    const issues: RenderingIssue[] = []
    const longTasks = Array.from(this.metrics.values())
      .filter(m => m.category === 'longtask')
    
    if (longTasks.length > 0) {
      const avgDuration = longTasks.reduce((sum, task) => 
        sum + task.data.duration, 0) / longTasks.length
      
      issues.push({
        type: 'long-tasks',
        severity: 'high',
        description: `检测到${longTasks.length}个长任务，平均耗时${avgDuration.toFixed(2)}ms`,
        suggestion: '使用时间切片或Web Workers优化长任务'
      })
    }
    
    return issues
  }
  
  // 分析内存问题
  private analyzeMemoryIssues(): MemoryIssue[] {
    const issues: MemoryIssue[] = []
    
    if ('memory' in performance) {
      const memory = (performance as any).memory
      const usageRatio = memory.usedJSHeapSize / memory.jsHeapSizeLimit
      
      if (usageRatio > 0.8) {
        issues.push({
          type: 'high-memory-usage',
          severity: 'high',
          description: `内存使用率过高: ${(usageRatio * 100).toFixed(1)}%`,
          suggestion: '检查内存泄漏，优化数据结构'
        })
      }
    }
    
    return issues
  }
  
  // 分析网络问题
  private analyzeNetworkIssues(): NetworkIssue[] {
    const issues: NetworkIssue[] = []
    const resourceMetrics = Array.from(this.metrics.values())
      .filter(m => m.category === 'resource')
    
    // 检查大文件
    const largeResources = resourceMetrics.filter(m => 
      m.data.transferSize > 1024 * 1024 // 1MB
    )
    
    if (largeResources.length > 0) {
      issues.push({
        type: 'large-resources',
        severity: 'medium',
        description: `发现${largeResources.length}个大文件资源`,
        suggestion: '考虑资源压缩和代码分割'
      })
    }
    
    // 检查慢请求
    const slowResources = resourceMetrics.filter(m => 
      m.data.duration > 3000 // 3秒
    )
    
    if (slowResources.length > 0) {
      issues.push({
        type: 'slow-requests',
        severity: 'high',
        description: `发现${slowResources.length}个慢请求`,
        suggestion: '优化服务器响应时间或使用CDN'
      })
    }
    
    return issues
  }
  
  // 生成优化建议
  private generateRecommendations(analysis: PerformanceAnalysis): string[] {
    const recommendations: string[] = []
    
    // 基于问题生成建议
    const allIssues = [
      ...analysis.loadingIssues,
      ...analysis.renderingIssues,
      ...analysis.memoryIssues,
      ...analysis.networkIssues
    ]
    
    const highSeverityIssues = allIssues.filter(issue => issue.severity === 'high')
    
    if (highSeverityIssues.length > 0) {
      recommendations.push('优先解决高严重性性能问题')
    }
    
    // 通用建议
    recommendations.push(
      '启用生产环境构建优化',
      '使用CDN加速静态资源',
      '实施适当的缓存策略',
      '监控Core Web Vitals指标'
    )
    
    return recommendations
  }
  
  // 获取性能报告
  getPerformanceReport(): PerformanceReport {
    const analysis = this.analyzeBottlenecks()
    
    return {
      timestamp: new Date().toISOString(),
      metrics: this.getMetricsSummary(),
      analysis,
      optimizations: Array.from(this.optimizations.values()),
      score: this.calculatePerformanceScore(analysis)
    }
  }
  
  // 获取指标摘要
  private getMetricsSummary(): MetricsSummary {
    const navigationMetrics = Array.from(this.metrics.values())
      .filter(m => m.category === 'navigation')
    
    const resourceMetrics = Array.from(this.metrics.values())
      .filter(m => m.category === 'resource')
    
    return {
      totalMetrics: this.metrics.size,
      navigationCount: navigationMetrics.length,
      resourceCount: resourceMetrics.length,
      averageLoadTime: this.calculateAverageLoadTime(navigationMetrics),
      totalTransferSize: this.calculateTotalTransferSize(resourceMetrics)
    }
  }
  
  // 计算平均加载时间
  private calculateAverageLoadTime(metrics: PerformanceMetric[]): number {
    if (metrics.length === 0) return 0
    
    const totalTime = metrics.reduce((sum, metric) => 
      sum + metric.data.duration, 0)
    
    return totalTime / metrics.length
  }
  
  // 计算总传输大小
  private calculateTotalTransferSize(metrics: PerformanceMetric[]): number {
    return metrics.reduce((sum, metric) => 
      sum + (metric.data.transferSize || 0), 0)
  }
  
  // 计算性能分数
  private calculatePerformanceScore(analysis: PerformanceAnalysis): number {
    let score = 100
    
    // 根据问题严重性扣分
    const allIssues = [
      ...analysis.loadingIssues,
      ...analysis.renderingIssues,
      ...analysis.memoryIssues,
      ...analysis.networkIssues
    ]
    
    allIssues.forEach(issue => {
      switch (issue.severity) {
        case 'high':
          score -= 15
          break
        case 'medium':
          score -= 10
          break
        case 'low':
          score -= 5
          break
      }
    })
    
    return Math.max(0, score)
  }
  
  // 清理资源
  dispose(): void {
    this.observers.forEach(observer => observer.disconnect())
    this.observers = []
    this.metrics.clear()
  }
}

// 类型定义
interface OptimizationStrategy {
  name: string
  strategies: string[]
  priority: 'high' | 'medium' | 'low'
  impact: 'high' | 'medium' | 'low'
}

interface PerformanceMetric {
  category: string
  timestamp: number
  data: any
}

interface PerformanceAnalysis {
  loadingIssues: LoadingIssue[]
  renderingIssues: RenderingIssue[]
  memoryIssues: MemoryIssue[]
  networkIssues: NetworkIssue[]
  recommendations: string[]
}

interface LoadingIssue {
  type: string
  severity: 'high' | 'medium' | 'low'
  description: string
  suggestion: string
}

interface RenderingIssue {
  type: string
  severity: 'high' | 'medium' | 'low'
  description: string
  suggestion: string
}

interface MemoryIssue {
  type: string
  severity: 'high' | 'medium' | 'low'
  description: string
  suggestion: string
}

interface NetworkIssue {
  type: string
  severity: 'high' | 'medium' | 'low'
  description: string
  suggestion: string
}

interface PerformanceReport {
  timestamp: string
  metrics: MetricsSummary
  analysis: PerformanceAnalysis
  optimizations: OptimizationStrategy[]
  score: number
}

interface MetricsSummary {
  totalMetrics: number
  navigationCount: number
  resourceCount: number
  averageLoadTime: number
  totalTransferSize: number
}

1.2 Core Web Vitals 监控

// Core Web Vitals 监控器
class CoreWebVitalsMonitor {
  private vitals: Map<string, VitalMetric> = new Map()
  private thresholds: VitalThresholds
  
  constructor() {
    this.thresholds = {
      LCP: { good: 2500, needsImprovement: 4000 },
      FID: { good: 100, needsImprovement: 300 },
      CLS: { good: 0.1, needsImprovement: 0.25 },
      FCP: { good: 1800, needsImprovement: 3000 },
      TTFB: { good: 800, needsImprovement: 1800 }
    }
    
    this.initializeMonitoring()
  }
  
  // 初始化监控
  private initializeMonitoring(): void {
    // 监控 LCP (Largest Contentful Paint)
    this.observeLCP()
    
    // 监控 FID (First Input Delay)
    this.observeFID()
    
    // 监控 CLS (Cumulative Layout Shift)
    this.observeCLS()
    
    // 监控 FCP (First Contentful Paint)
    this.observeFCP()
    
    // 监控 TTFB (Time to First Byte)
    this.observeTTFB()
  }
  
  // 监控 LCP
  private observeLCP(): void {
    if ('PerformanceObserver' in window) {
      const observer = new PerformanceObserver((list) => {
        const entries = list.getEntries()
        const lastEntry = entries[entries.length - 1] as PerformanceEntry
        
        this.recordVital('LCP', {
          value: lastEntry.startTime,
          timestamp: Date.now(),
          element: (lastEntry as any).element?.tagName || 'unknown'
        })
      })
      
      observer.observe({ entryTypes: ['largest-contentful-paint'] })
    }
  }
  
  // 监控 FID
  private observeFID(): void {
    if ('PerformanceObserver' in window) {
      const observer = new PerformanceObserver((list) => {
        for (const entry of list.getEntries()) {
          this.recordVital('FID', {
            value: entry.processingStart - entry.startTime,
            timestamp: Date.now(),
            eventType: (entry as any).name
          })
        }
      })
      
      observer.observe({ entryTypes: ['first-input'] })
    }
  }
  
  // 监控 CLS
  private observeCLS(): void {
    if ('PerformanceObserver' in window) {
      let clsValue = 0
      
      const observer = new PerformanceObserver((list) => {
        for (const entry of list.getEntries()) {
          if (!(entry as any).hadRecentInput) {
            clsValue += (entry as any).value
          }
        }
        
        this.recordVital('CLS', {
          value: clsValue,
          timestamp: Date.now()
        })
      })
      
      observer.observe({ entryTypes: ['layout-shift'] })
    }
  }
  
  // 监控 FCP
  private observeFCP(): void {
    if ('PerformanceObserver' in window) {
      const observer = new PerformanceObserver((list) => {
        for (const entry of list.getEntries()) {
          if (entry.name === 'first-contentful-paint') {
            this.recordVital('FCP', {
              value: entry.startTime,
              timestamp: Date.now()
            })
          }
        }
      })
      
      observer.observe({ entryTypes: ['paint'] })
    }
  }
  
  // 监控 TTFB
  private observeTTFB(): void {
    if ('PerformanceObserver' in window) {
      const observer = new PerformanceObserver((list) => {
        for (const entry of list.getEntries()) {
          const navEntry = entry as PerformanceNavigationTiming
          const ttfb = navEntry.responseStart - navEntry.requestStart
          
          this.recordVital('TTFB', {
            value: ttfb,
            timestamp: Date.now()
          })
        }
      })
      
      observer.observe({ entryTypes: ['navigation'] })
    }
  }
  
  // 记录 Vital 指标
  private recordVital(name: string, data: any): void {
    this.vitals.set(name, {
      name,
      value: data.value,
      timestamp: data.timestamp,
      rating: this.getRating(name, data.value),
      metadata: data
    })
  }
  
  // 获取评级
  private getRating(vitalName: string, value: number): 'good' | 'needs-improvement' | 'poor' {
    const threshold = this.thresholds[vitalName as keyof VitalThresholds]
    if (!threshold) return 'poor'
    
    if (value <= threshold.good) return 'good'
    if (value <= threshold.needsImprovement) return 'needs-improvement'
    return 'poor'
  }
  
  // 获取 Vitals 报告
  getVitalsReport(): VitalsReport {
    const vitalsArray = Array.from(this.vitals.values())
    
    return {
      timestamp: new Date().toISOString(),
      vitals: vitalsArray,
      summary: {
        totalVitals: vitalsArray.length,
        goodCount: vitalsArray.filter(v => v.rating === 'good').length,
        needsImprovementCount: vitalsArray.filter(v => v.rating === 'needs-improvement').length,
        poorCount: vitalsArray.filter(v => v.rating === 'poor').length
      },
      recommendations: this.generateVitalsRecommendations(vitalsArray)
    }
  }
  
  // 生成 Vitals 建议
  private generateVitalsRecommendations(vitals: VitalMetric[]): string[] {
    const recommendations: string[] = []
    
    vitals.forEach(vital => {
      if (vital.rating === 'poor') {
        switch (vital.name) {
          case 'LCP':
            recommendations.push('优化LCP: 减少服务器响应时间，优化资源加载')
            break
          case 'FID':
            recommendations.push('优化FID: 减少JavaScript执行时间，使用Web Workers')
            break
          case 'CLS':
            recommendations.push('优化CLS: 为图片和广告设置尺寸，避免动态内容插入')
            break
          case 'FCP':
            recommendations.push('优化FCP: 减少阻塞渲染的资源，优化关键渲染路径')
            break
          case 'TTFB':
            recommendations.push('优化TTFB: 优化服务器配置，使用CDN')
            break
        }
      }
    })
    
    return recommendations
  }
}

// 类型定义
interface VitalThresholds {
  LCP: { good: number; needsImprovement: number }
  FID: { good: number; needsImprovement: number }
  CLS: { good: number; needsImprovement: number }
  FCP: { good: number; needsImprovement: number }
  TTFB: { good: number; needsImprovement: number }
}

interface VitalMetric {
  name: string
  value: number
  timestamp: number
  rating: 'good' | 'needs-improvement' | 'poor'
  metadata: any
}

interface VitalsReport {
  timestamp: string
  vitals: VitalMetric[]
  summary: {
    totalVitals: number
    goodCount: number
    needsImprovementCount: number
    poorCount: number
  }
  recommendations: string[]
}

2. 组件级性能优化

2.1 组件性能优化器

// 组件性能优化器
class ComponentPerformanceOptimizer {
  private componentMetrics: Map<string, ComponentMetric> = new Map()
  private optimizationRules: OptimizationRule[] = []
  
  constructor() {
    this.initializeOptimizationRules()
  }
  
  // 初始化优化规则
  private initializeOptimizationRules(): void {
    this.optimizationRules = [
      {
        name: 'large-list-optimization',
        condition: (metric) => metric.childrenCount > 100,
        suggestion: '使用虚拟滚动优化大列表渲染',
        priority: 'high'
      },
      {
        name: 'frequent-updates',
        condition: (metric) => metric.updateFrequency > 10,
        suggestion: '使用防抖或节流优化频繁更新',
        priority: 'medium'
      },
      {
        name: 'deep-nesting',
        condition: (metric) => metric.nestingDepth > 10,
        suggestion: '减少组件嵌套深度，考虑组件拆分',
        priority: 'medium'
      },
      {
        name: 'large-props',
        condition: (metric) => metric.propsSize > 1024 * 10, // 10KB
        suggestion: '减少props大小，考虑使用provide/inject',
        priority: 'low'
      }
    ]
  }
  
  // 分析组件性能
  analyzeComponent(componentName: string, instance: any): ComponentAnalysis {
    const metric = this.collectComponentMetric(componentName, instance)
    this.componentMetrics.set(componentName, metric)
    
    const issues = this.identifyIssues(metric)
    const optimizations = this.suggestOptimizations(metric)
    
    return {
      componentName,
      metric,
      issues,
      optimizations,
      score: this.calculateComponentScore(metric, issues)
    }
  }
  
  // 收集组件指标
  private collectComponentMetric(componentName: string, instance: any): ComponentMetric {
    const startTime = performance.now()
    
    // 模拟指标收集
    const metric: ComponentMetric = {
      name: componentName,
      renderTime: 0,
      updateCount: 0,
      updateFrequency: 0,
      childrenCount: this.countChildren(instance),
      nestingDepth: this.calculateNestingDepth(instance),
      propsSize: this.calculatePropsSize(instance),
      memoryUsage: this.estimateMemoryUsage(instance),
      lastUpdate: Date.now()
    }
    
    const endTime = performance.now()
    metric.renderTime = endTime - startTime
    
    return metric
  }
  
  // 计算子组件数量
  private countChildren(instance: any): number {
    if (!instance || !instance.$children) return 0
    
    let count = instance.$children.length
    instance.$children.forEach((child: any) => {
      count += this.countChildren(child)
    })
    
    return count
  }
  
  // 计算嵌套深度
  private calculateNestingDepth(instance: any, depth: number = 0): number {
    if (!instance || !instance.$children || instance.$children.length === 0) {
      return depth
    }
    
    let maxDepth = depth
    instance.$children.forEach((child: any) => {
      const childDepth = this.calculateNestingDepth(child, depth + 1)
      maxDepth = Math.max(maxDepth, childDepth)
    })
    
    return maxDepth
  }
  
  // 计算Props大小
  private calculatePropsSize(instance: any): number {
    if (!instance || !instance.$props) return 0
    
    try {
      return JSON.stringify(instance.$props).length
    } catch {
      return 0
    }
  }
  
  // 估算内存使用
  private estimateMemoryUsage(instance: any): number {
    // 简化实现，实际应该更精确
    const baseSize = 1024 // 1KB基础大小
    const propsSize = this.calculatePropsSize(instance)
    const childrenSize = this.countChildren(instance) * 512 // 每个子组件512B
    
    return baseSize + propsSize + childrenSize
  }
  
  // 识别性能问题
  private identifyIssues(metric: ComponentMetric): PerformanceIssue[] {
    const issues: PerformanceIssue[] = []
    
    // 渲染时间过长
    if (metric.renderTime > 16) { // 超过一帧时间
      issues.push({
        type: 'slow-render',
        severity: 'high',
        description: `组件渲染时间过长: ${metric.renderTime.toFixed(2)}ms`,
        impact: 'user-experience'
      })
    }
    
    // 更新频率过高
    if (metric.updateFrequency > 60) { // 每秒超过60次更新
      issues.push({
        type: 'frequent-updates',
        severity: 'medium',
        description: `组件更新频率过高: ${metric.updateFrequency}/s`,
        impact: 'performance'
      })
    }
    
    // 内存使用过大
    if (metric.memoryUsage > 1024 * 100) { // 100KB
      issues.push({
        type: 'high-memory',
        severity: 'medium',
        description: `组件内存使用过大: ${(metric.memoryUsage / 1024).toFixed(2)}KB`,
        impact: 'memory'
      })
    }
    
    return issues
  }
  
  // 建议优化方案
  private suggestOptimizations(metric: ComponentMetric): OptimizationSuggestion[] {
    const suggestions: OptimizationSuggestion[] = []
    
    this.optimizationRules.forEach(rule => {
      if (rule.condition(metric)) {
        suggestions.push({
          rule: rule.name,
          suggestion: rule.suggestion,
          priority: rule.priority,
          estimatedImpact: this.estimateOptimizationImpact(rule, metric)
        })
      }
    })
    
    return suggestions
  }
  
  // 估算优化影响
  private estimateOptimizationImpact(rule: OptimizationRule, metric: ComponentMetric): string {
    switch (rule.name) {
      case 'large-list-optimization':
        return `可减少${Math.floor(metric.childrenCount * 0.8)}个DOM节点`
      case 'frequent-updates':
        return `可减少${Math.floor(metric.updateFrequency * 0.7)}次/秒更新`
      case 'deep-nesting':
        return `可减少${metric.nestingDepth - 5}层嵌套`
      case 'large-props':
        return `可减少${Math.floor(metric.propsSize * 0.5)}字节内存`
      default:
        return '性能提升'
    }
  }
  
  // 计算组件分数
  private calculateComponentScore(metric: ComponentMetric, issues: PerformanceIssue[]): number {
    let score = 100
    
    // 根据渲染时间扣分
    if (metric.renderTime > 16) {
      score -= Math.min(30, metric.renderTime - 16)
    }
    
    // 根据问题严重性扣分
    issues.forEach(issue => {
      switch (issue.severity) {
        case 'high':
          score -= 20
          break
        case 'medium':
          score -= 10
          break
        case 'low':
          score -= 5
          break
      }
    })
    
    return Math.max(0, score)
  }
  
  // 获取组件性能报告
  getComponentReport(): ComponentPerformanceReport {
    const components = Array.from(this.componentMetrics.values())
    
    return {
      timestamp: new Date().toISOString(),
      totalComponents: components.length,
      averageScore: this.calculateAverageScore(components),
      topIssues: this.getTopIssues(components),
      recommendations: this.getTopRecommendations(components)
    }
  }
  
  // 计算平均分数
  private calculateAverageScore(components: ComponentMetric[]): number {
    if (components.length === 0) return 0
    
    const totalScore = components.reduce((sum, component) => {
      const analysis = this.analyzeComponent(component.name, null)
      return sum + analysis.score
    }, 0)
    
    return totalScore / components.length
  }
  
  // 获取主要问题
  private getTopIssues(components: ComponentMetric[]): string[] {
    const issueCount = new Map<string, number>()
    
    components.forEach(component => {
      const analysis = this.analyzeComponent(component.name, null)
      analysis.issues.forEach(issue => {
        issueCount.set(issue.type, (issueCount.get(issue.type) || 0) + 1)
      })
    })
    
    return Array.from(issueCount.entries())
      .sort((a, b) => b[1] - a[1])
      .slice(0, 5)
      .map(([type, count]) => `${type}: ${count}个组件`)
  }
  
  // 获取主要建议
  private getTopRecommendations(components: ComponentMetric[]): string[] {
    const recommendationCount = new Map<string, number>()
    
    components.forEach(component => {
      const analysis = this.analyzeComponent(component.name, null)
      analysis.optimizations.forEach(opt => {
        recommendationCount.set(opt.suggestion, (recommendationCount.get(opt.suggestion) || 0) + 1)
      })
    })
    
    return Array.from(recommendationCount.entries())
      .sort((a, b) => b[1] - a[1])
      .slice(0, 5)
      .map(([suggestion]) => suggestion)
  }
}

// 类型定义
interface ComponentMetric {
  name: string
  renderTime: number
  updateCount: number
  updateFrequency: number
  childrenCount: number
  nestingDepth: number
  propsSize: number
  memoryUsage: number
  lastUpdate: number
}

interface OptimizationRule {
  name: string
  condition: (metric: ComponentMetric) => boolean
  suggestion: string
  priority: 'high' | 'medium' | 'low'
}

interface ComponentAnalysis {
  componentName: string
  metric: ComponentMetric
  issues: PerformanceIssue[]
  optimizations: OptimizationSuggestion[]
  score: number
}

interface PerformanceIssue {
  type: string
  severity: 'high' | 'medium' | 'low'
  description: string
  impact: string
}

interface OptimizationSuggestion {
  rule: string
  suggestion: string
  priority: 'high' | 'medium' | 'low'
  estimatedImpact: string
}

interface ComponentPerformanceReport {
  timestamp: string
  totalComponents: number
  averageScore: number
  topIssues: string[]
  recommendations: string[]
}

3. 实践练习

1. 性能监控实践：

   • 集成性能监控工具
   • 实现Core Web Vitals监控
   • 建立性能预警机制

2. 组件优化实践：

   • 优化大数据量组件
   • 实现组件懒加载
   • 优化组件渲染性能

3. 应用级优化：

   • 实现代码分割
   • 优化资源加载
   • 建立缓存策略

4. 学习资源

• Web Performance
• Core Web Vitals
• Performance API
• Vue.js Performance Guide

5. 作业

• 实现完整的性能监控系统
• 优化一个复杂的Element Plus应用
• 建立性能优化最佳实践文档
• 创建性能测试自动化流程

总结

通过第84天的学习，我们全面掌握了：

1. 性能优化策略：建立了完整的性能优化体系
2. 监控体系：实现了Core Web Vitals和组件级性能监控
3. 优化实践：掌握了从组件到应用的全面优化技巧
4. 质量保证：建立了性能质量保证流程

这些技能将帮助我们构建高性能、用户体验优秀的Element Plus应用。