HTML to SVG JavaScript: Production-Ready Implementation Guide

Introduction: HTML to SVG Conversion in Production Environments

Core Conversion Techniques: Native vs. Library-Based Approaches

Method 1: Native foreignObject Implementation (Recommended for Simple HTML)

/**
 * Production-ready HTML to SVG converter using foreignObject
 * Handles CSS styling, responsive layouts, and proper namespace declarations
 */
class HtmlToSvgConverter {
  constructor(options = {}) {
    this.defaultOptions = {
      width: 800,
      height: 600,
      backgroundColor: '#ffffff',
      includeStyles: true,
      preserveAspectRatio: 'xMidYMid meet',
      ...options
    };
  }

  /**
   * Convert HTML string to SVG using foreignObject
   * @param {string} htmlString - Raw HTML content
   * @param {Object} options - Conversion options
   * @returns {Promise<string>} - SVG string
   */
  async convertWithForeignObject(htmlString, options = {}) {
    const config = { ...this.defaultOptions, ...options };
    
    try {
      // Validate HTML input
      this.validateHtmlInput(htmlString);
      
      // Create SVG container with proper namespaces
      const svg = this.createSvgContainer(config);
      
      // Create foreignObject with HTML content
      const foreignObject = this.createForeignObject(htmlString, config);
      svg.appendChild(foreignObject);
      
      // Serialize to string with proper XML declaration
      return this.serializeSvg(svg);
      
    } catch (error) {
      throw new Error('HTML to SVG conversion failed: ' + error.message);
    }
  }

  validateHtmlInput(htmlString) {
    if (!htmlString || typeof htmlString !== 'string') {
      throw new Error('Invalid HTML input: string expected');
    }
    
    const trimmed = htmlString.trim();
    if (!trimmed.includes('<') || !trimmed.includes('>')) {
      throw new Error('Invalid HTML: Missing HTML tags');
    }
  }

  createSvgContainer(config) {
    const svg = document.createElementNS('http://www.w3.org/2000/svg', 'svg');
    svg.setAttribute('width', config.width);
    svg.setAttribute('height', config.height);
    svg.setAttribute('viewBox', '0 0 ' + config.width + ' ' + config.height);
    svg.setAttribute('preserveAspectRatio', config.preserveAspectRatio);
    svg.setAttribute('xmlns', 'http://www.w3.org/2000/svg');
    svg.setAttribute('xmlns:xhtml', 'http://www.w3.org/1999/xhtml');
    
    // Add background if specified
    if (config.backgroundColor && config.backgroundColor !== 'transparent') {
      const background = document.createElementNS('http://www.w3.org/2000/svg', 'rect');
      background.setAttribute('width', '100%');
      background.setAttribute('height', '100%');
      background.setAttribute('fill', config.backgroundColor);
      svg.appendChild(background);
    }
    
    return svg;
  }

  createForeignObject(htmlString, config) {
    const foreignObject = document.createElementNS('http://www.w3.org/2000/svg', 'foreignObject');
    foreignObject.setAttribute('width', '100%');
    foreignObject.setAttribute('height', '100%');
    foreignObject.setAttribute('x', '0');
    foreignObject.setAttribute('y', '0');
    
    // Create XHTML container
    const xhtmlContainer = document.createElementNS('http://www.w3.org/1999/xhtml', 'div');
    xhtmlContainer.setAttribute('xmlns', 'http://www.w3.org/1999/xhtml');
    
    // Apply container styles
    xhtmlContainer.style.cssText = '
      width: ' + config.width + 'px;
      height: ' + config.height + 'px;
      margin: 0;
      padding: 0;
      box-sizing: border-box;
      font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    ';
    
    // Insert HTML content
    xhtmlContainer.innerHTML = htmlString;
    foreignObject.appendChild(xhtmlContainer);
    
    return foreignObject;
  }

  serializeSvg(svgElement) {
    const serializer = new XMLSerializer();
    const svgString = serializer.serializeToString(svgElement);
    
    // Add XML declaration for proper SVG file format
    return '<?xml version="1.0" encoding="UTF-8"?>\n' + svgString;
  }
}

// Usage example
const converter = new HtmlToSvgConverter();
const svgOutput = await converter.convertWithForeignObject(
  '<h1 style="color: blue;">Hello SVG!</h1>',
  { width: 400, height: 200 }
);

Method 2: html2canvas Integration (Production Implementation)

/**
 * Advanced HTML to SVG converter using html2canvas
 * Based on production patterns from SVG AI converter system
 */
class Html2CanvasSvgConverter {
  constructor() {
    this.html2canvas = null;
    this.isLibraryLoaded = false;
  }

  /**
   * Lazy load html2canvas library
   */
  async ensureLibraryLoaded() {
    if (this.isLibraryLoaded) return;
    
    try {
      if (typeof window === 'undefined') {
        throw new Error('html2canvas requires browser environment');
      }
      
      // Dynamic import for optimal bundle size
      const html2canvasModule = await import('html2canvas');
      this.html2canvas = html2canvasModule.default;
      this.isLibraryLoaded = true;
      
    } catch (error) {
      throw new Error('Failed to load html2canvas: ' + error.message);
    }
  }

  /**
   * Convert HTML to SVG via canvas rendering
   * @param {string} htmlString - HTML content
   * @param {Object} options - Rendering options
   * @returns {Promise<string>} - SVG string
   */
  async convertWithCanvas(htmlString, options = {}) {
    await this.ensureLibraryLoaded();
    
    const config = {
      width: 800,
      height: 600,
      scale: 2, // High DPI rendering
      backgroundColor: '#ffffff',
      logging: false,
      useCORS: true,
      allowTaint: false,
      ...options
    };

    let container = null;
    
    try {
      // Create temporary DOM container
      container = this.createTempContainer(htmlString, config);
      
      // Configure html2canvas options
      const canvasOptions = {
        scale: config.scale,
        width: config.width,
        height: config.height,
        backgroundColor: config.backgroundColor,
        logging: config.logging,
        useCORS: config.useCORS,
        allowTaint: config.allowTaint,
        foreignObjectRendering: false, // Use for better compatibility
        removeContainer: true
      };
      
      // Render to canvas
      const canvas = await this.html2canvas(container, canvasOptions);
      
      // Convert canvas to SVG
      const svgString = this.canvasToSvg(canvas, config);
      
      return svgString;
      
    } finally {
      // Always cleanup temporary container
      if (container && container.parentNode) {
        container.parentNode.removeChild(container);
      }
    }
  }

  createTempContainer(htmlString, config) {
    const container = document.createElement('div');
    
    // Position off-screen to avoid visual flash
    container.style.cssText = '
      position: absolute;
      left: -9999px;
      top: -9999px;
      width: ' + config.width + 'px;
      height: ' + config.height + 'px;
      overflow: hidden;
      background-color: ' + config.backgroundColor + ';
      font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    ';
    
    // Create content wrapper
    const wrapper = document.createElement('div');
    wrapper.innerHTML = htmlString;
    container.appendChild(wrapper);
    
    // Append to document for rendering
    document.body.appendChild(container);
    
    return container;
  }

  canvasToSvg(canvas, config) {
    const width = canvas.width;
    const height = canvas.height;
    const dataUrl = canvas.toDataURL('image/png');
    
    return '<?xml version="1.0" encoding="UTF-8"?>\n<svg xmlns="http://www.w3.org/2000/svg" \n     width="' + width + '" \n     height="' + height + '" \n     viewBox="0 0 ' + width + ' ' + height + '">' + '
' +
  '<defs>' + '
' +
'    <style type="text/css">' + '
' +
'      .html-content { image-rendering: -webkit-optimize-contrast; }' + '
' +
'    </style>' + '
' +
'  </defs>' + '
' +
'  <image ' + '
' +
'    class="html-content"' + '
' +
'    x="0" ' + '
' +
'    y="0" ' + '
' +
'    width="' + width + '" \n    height="' + height + '" \n    href="' + dataUrl + '" ' + '
' +
'    preserveAspectRatio="none"/>' + '
' +
'</svg>';
  }
}

// Production usage with error handling
async function convertHtmlToSvgProduction(htmlContent, options = {}) {
  const converter = new Html2CanvasSvgConverter();
  
  try {
    const result = await converter.convertWithCanvas(htmlContent, {
      width: options.width || 1200,
      height: options.height || 800,
      scale: options.scale || 2,
      backgroundColor: options.background || '#ffffff'
    });
    
    return {
      success: true,
      data: result,
      mimeType: 'image/svg+xml'
    };
    
  } catch (error) {
    return {
      success: false,
      error: error.message,
      fallback: 'Try using our [HTML to SVG converter tool](/convert/html-to-svg) for complex conversions'
    };
  }
}

Advanced Integration Patterns

Framework Integration Examples

React/Next.js Integration

/**
 * React component for HTML to SVG conversion
 * Handles client-side rendering with proper error boundaries
 */
import React, { useState, useCallback, useRef } from 'react';
import { Html2CanvasSvgConverter } from '../lib/html-to-svg';

interface HtmlToSvgConverterProps {
  onConversion?: (result: ConversionResult) => void;
  defaultOptions?: ConversionOptions;
}

interface ConversionResult {
  success: boolean;
  data?: string;
  error?: string;
  metadata?: {
    width: number;
    height: number;
    size: string;
    processingTime: number;
  };
}

export const HtmlToSvgConverter: React.FC<HtmlToSvgConverterProps> = ({
  onConversion,
  defaultOptions = {}
}) => {
  const [isConverting, setIsConverting] = useState(false);
  const [result, setResult] = useState<ConversionResult | null>(null);
  const converterRef = useRef<Html2CanvasSvgConverter>();
  
  // Initialize converter with memoization
  const getConverter = useCallback(() => {
    if (!converterRef.current) {
      converterRef.current = new Html2CanvasSvgConverter();
    }
    return converterRef.current;
  }, []);

  const handleConversion = useCallback(async (htmlContent: string, options = {}) => {
    setIsConverting(true);
    setResult(null);
    
    const startTime = performance.now();
    
    try {
      const converter = getConverter();
      const config = { ...defaultOptions, ...options };
      
      const svgOutput = await converter.convertWithCanvas(htmlContent, config);
      
      const processingTime = performance.now() - startTime;
      const conversionResult: ConversionResult = {
        success: true,
        data: svgOutput,
        metadata: {
          width: config.width || 800,
          height: config.height || 600,
          size: (svgOutput.length / 1024).toFixed(2) + 'KB',
          processingTime: Math.round(processingTime)
        }
      };
      
      setResult(conversionResult);
      onConversion?.(conversionResult);
      
    } catch (error) {
      const errorResult: ConversionResult = {
        success: false,
        error: error instanceof Error ? error.message : 'Conversion failed'
      };
      
      setResult(errorResult);
      onConversion?.(errorResult);
      
    } finally {
      setIsConverting(false);
    }
  }, [defaultOptions, onConversion, getConverter]);

  return (
    <div className="html-to-svg-converter">
      {/* Converter UI implementation */}
      <button 
        onClick={() => handleConversion('<h1>Test</h1>')}
        disabled={isConverting}
        className="convert-btn"
      >
        {isConverting ? 'Converting...' : 'Convert to SVG'}
      </button>
      
      {result && (
        <div className="conversion-result">
          {result.success ? (
            <div className="success-result">
              <p>✅ Conversion successful!</p>
              <p>Size: {result.metadata?.size}</p>
              <p>Processing: {result.metadata?.processingTime}ms</p>
            </div>
          ) : (
            <div className="error-result">
              <p>❌ Error: {result.error}</p>
              <p>Try our <a href="/convert/html-to-svg">HTML to SVG tool</a> for complex conversions</p>
            </div>
          )}
        </div>
      )}
    </div>
  );
};

Vue.js Integration

/**
 * Vue 3 composable for HTML to SVG conversion
 * Provides reactive state and error handling
 */
import { ref, computed, onUnmounted } from 'vue';
import { Html2CanvasSvgConverter } from '../lib/html-to-svg';

export function useHtmlToSvgConverter(defaultOptions = {}) {
  const isConverting = ref(false);
  const result = ref(null);
  const error = ref(null);
  const converter = ref(null);

  // Initialize converter lazily
  const getConverter = () => {
    if (!converter.value) {
      converter.value = new Html2CanvasSvgConverter();
    }
    return converter.value;
  };

  // Reactive computed properties
  const isReady = computed(() => !isConverting.value);
  const hasResult = computed(() => result.value !== null);
  const hasError = computed(() => error.value !== null);

  const convert = async (htmlContent, options = {}) => {
    isConverting.value = true;
    error.value = null;
    result.value = null;

    try {
      const config = { ...defaultOptions, ...options };
      const svgOutput = await getConverter().convertWithCanvas(htmlContent, config);
      
      result.value = {
        svg: svgOutput,
        size: (svgOutput.length / 1024).toFixed(2) + 'KB',
        timestamp: new Date().toISOString()
      };
      
    } catch (err) {
      error.value = err.message;
      console.error('HTML to SVG conversion failed:', err);
    } finally {
      isConverting.value = false;
    }
  };

  const reset = () => {
    result.value = null;
    error.value = null;
  };

  // Cleanup on unmount
  onUnmounted(() => {
    converter.value = null;
  });

  return {
    isConverting: readonly(isConverting),
    result: readonly(result),
    error: readonly(error),
    isReady,
    hasResult,
    hasError,
    convert,
    reset
  };
}

Enterprise Integration Patterns

API Gateway Integration

/**
 * Express.js API endpoint for HTML to SVG conversion
 * Handles rate limiting, validation, and caching
 */
import express from 'express';
import rateLimit from 'express-rate-limit';
import { body, validationResult } from 'express-validator';
import NodeCache from 'node-cache';
import { createHash } from 'crypto';

const app = express();
const cache = new NodeCache({ stdTTL: 3600 }); // 1 hour cache

// Rate limiting: 100 requests per hour per IP
const limiter = rateLimit({
  windowMs: 60 * 60 * 1000, // 1 hour
  max: 100,
  message: 'Too many conversion requests, please try again later'
});

// Validation middleware
const validateConversion = [
  body('html').notEmpty().withMessage('HTML content is required'),
  body('options.width').optional().isInt({ min: 100, max: 4000 }),
  body('options.height').optional().isInt({ min: 100, max: 4000 }),
  body('options.scale').optional().isFloat({ min: 0.5, max: 4 })
];

app.post('/api/convert/html-to-svg', 
  limiter,
  express.json({ limit: '10mb' }),
  validateConversion,
  async (req, res) => {
    // Validate input
    const errors = validationResult(req);
    if (!errors.isEmpty()) {
      return res.status(400).json({
        error: 'Validation failed',
        details: errors.array()
      });
    }

    const { html, options = {} } = req.body;
    
    // Generate cache key
    const cacheKey = createHash('sha256')
      .update(html + JSON.stringify(options))
      .digest('hex');
    
    // Check cache first
    const cached = cache.get(cacheKey);
    if (cached) {
      return res.json({
        success: true,
        data: cached,
        cached: true
      });
    }

    try {
      // Import converter dynamically for memory management
      const { Html2CanvasSvgConverter } = await import('../lib/html-to-svg');
      const converter = new Html2CanvasSvgConverter();
      
      const startTime = process.hrtime.bigint();
      const svgOutput = await converter.convertWithCanvas(html, {
        width: options.width || 800,
        height: options.height || 600,
        scale: options.scale || 2,
        backgroundColor: options.backgroundColor || '#ffffff'
      });
      const duration = Number(process.hrtime.bigint() - startTime) / 1000000; // ms

      const result = {
        svg: svgOutput,
        metadata: {
          size: svgOutput.length,
          sizeFormatted: (svgOutput.length / 1024).toFixed(2) + 'KB',
          processingTime: Math.round(duration),
          timestamp: new Date().toISOString()
        }
      };

      // Cache successful results
      cache.set(cacheKey, result);

      res.json({
        success: true,
        data: result
      });

    } catch (error) {
      console.error('Conversion error:', error);
      
      res.status(500).json({
        success: false,
        error: 'Conversion failed',
        message: error.message,
        fallback: 'Try our free HTML to SVG converter at /convert/html-to-svg'
      });
    }
  }
);

Security Hardening & XSS Prevention

/**
 * Security-hardened HTML sanitization for SVG conversion
 * Prevents XSS attacks and malicious code injection
 */
import DOMPurify from 'dompurify';
import { JSDOM } from 'jsdom';

class SecureHtmlToSvgConverter extends Html2CanvasSvgConverter {
  constructor(options = {}) {
    super(options);
    
    // Initialize DOMPurify with custom window
    const window = new JSDOM('').window;
    this.DOMPurify = DOMPurify(window);
    
    // Security configuration
    this.securityConfig = {
      ALLOWED_TAGS: [
        'div', 'span', 'p', 'h1', 'h2', 'h3', 'h4', 'h5', 'h6',
        'strong', 'em', 'b', 'i', 'u', 'ul', 'ol', 'li',
        'table', 'tr', 'td', 'th', 'thead', 'tbody'
      ],
      ALLOWED_ATTR: [
        'class', 'id', 'style', 'data-*'
      ],
      FORBID_TAGS: ['script', 'object', 'embed', 'iframe', 'form'],
      FORBID_ATTR: ['onclick', 'onload', 'onerror', 'onmouseover'],
      ...options.security
    };
  }

  /**
   * Sanitize HTML content before conversion
   * @param {string} htmlContent - Raw HTML content
   * @returns {string} - Sanitized HTML
   */
  sanitizeHtml(htmlContent) {
    if (!htmlContent || typeof htmlContent !== 'string') {
      throw new Error('Invalid HTML content provided');
    }

    // Remove potentially dangerous content
    const sanitized = this.DOMPurify.sanitize(htmlContent, this.securityConfig);
    
    // Additional security checks
    if (sanitized.includes('javascript:')) {
      throw new Error('JavaScript URLs are not allowed');
    }
    
    if (sanitized.includes('data:text/html')) {
      throw new Error('HTML data URLs are not allowed');
    }
    
    // Validate result is not empty after sanitization
    if (!sanitized.trim()) {
      throw new Error('HTML content was empty after sanitization');
    }
    
    return sanitized;
  }

  /**
   * Secure conversion with automatic sanitization
   */
  async convertSecurely(htmlContent, options = {}) {
    try {
      // Sanitize input first
      const cleanHtml = this.sanitizeHtml(htmlContent);
      
      // Log security events in production
      if (cleanHtml !== htmlContent.trim()) {
        console.warn('HTML content was sanitized during conversion');
      }
      
      // Convert using parent class method
      return await this.convertWithCanvas(cleanHtml, options);
      
    } catch (error) {
      // Log security-related errors
      if (error.message.includes('not allowed')) {
        console.error('Security violation detected:', error.message);
      }
      throw error;
    }
  }
}

// Usage example with security monitoring
const secureConverter = new SecureHtmlToSvgConverter({
  security: {
    // Custom security overrides
    ALLOWED_TAGS: ['div', 'span', 'h1', 'p'], // Minimal allowed tags
    ALLOWED_ATTR: ['class', 'style'] // Minimal allowed attributes
  }
});

// Production usage with monitoring
async function secureConversionWorkflow(userHtml, userId = null) {
  const startTime = Date.now();
  
  try {
    const result = await secureConverter.convertSecurely(userHtml, {
      width: 800,
      height: 600,
      scale: 1 // Lower scale for security
    });
    
    // Log successful conversion
    console.log('Secure conversion completed', {
      userId,
      processingTime: Date.now() - startTime,
      inputSize: userHtml.length,
      outputSize: result.length
    });
    
    return result;
    
  } catch (error) {
    // Log security incidents
    console.error('Secure conversion failed', {
      userId,
      error: error.message,
      inputLength: userHtml.length,
      timestamp: new Date().toISOString()
    });
    
    throw error;
  }
}

Multi-Format Conversion Pipeline

/**
 * Enterprise-grade multi-format conversion pipeline
 * HTML → SVG → PNG → PDF → Video workflow
 */
class EnterpriseConversionPipeline {
  constructor() {
    this.htmlConverter = new SecureHtmlToSvgConverter();
    this.metrics = {
      conversions: 0,
      errors: 0,
      totalProcessingTime: 0
    };
  }

  async processDocumentWorkflow(htmlContent, outputFormats = ['svg', 'png', 'pdf']) {
    const startTime = Date.now();
    const results = { success: false, outputs: {}, errors: [] };
    
    try {
      // Step 1: HTML to SVG (always required)
      const svgResult = await this.htmlConverter.convertSecurely(htmlContent, {
        width: 1200,
        height: 800,
        scale: 2
      });
      results.outputs.svg = svgResult;
      
      // Step 2: SVG to PNG (high-quality raster)
      if (outputFormats.includes('png')) {
        try {
          const pngResult = await this.convertSvgToPng(svgResult, {
            quality: 0.95,
            dpi: 300
          });
          results.outputs.png = pngResult;
        } catch (error) {
          results.errors.push({ format: 'png', error: error.message });
        }
      }
      
      // Step 3: SVG to PDF (document export)
      if (outputFormats.includes('pdf')) {
        try {
          const pdfResult = await this.convertSvgToPdf(svgResult, {
            format: 'A4',
            orientation: 'landscape'
          });
          results.outputs.pdf = pdfResult;
        } catch (error) {
          results.errors.push({ format: 'pdf', error: error.message });
        }
      }
      
      // Step 4: SVG to Video (animation export)
      if (outputFormats.includes('video')) {
        try {
          const videoResult = await this.convertSvgToVideo(svgResult, {
            duration: 5,
            fps: 30,
            format: 'mp4'
          });
          results.outputs.video = videoResult;
        } catch (error) {
          results.errors.push({ format: 'video', error: error.message });
        }
      }
      
      results.success = Object.keys(results.outputs).length > 0;
      
      // Update metrics
      this.metrics.conversions++;
      this.metrics.totalProcessingTime += Date.now() - startTime;
      
      return results;
      
    } catch (error) {
      this.metrics.errors++;
      throw new Error('Conversion pipeline failed: ' + error.message);
    }
  }

  async convertSvgToPng(svgData, options = {}) {
    // Integration with our SVG to PNG converter
    // See: /convert/svg-to-png for full implementation
    const response = await fetch('/api/convert/svg-to-png', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ 
        svg: svgData,
        width: options.width || 1200,
        height: options.height || 800,
        quality: options.quality || 0.9,
        dpi: options.dpi || 150
      })
    });
    
    if (!response.ok) {
      throw new Error('PNG conversion failed: ' + response.statusText);
    }
    
    return await response.blob();
  }

  async convertSvgToPdf(svgData, options = {}) {
    // Integration with our SVG to PDF converter
    // See: /convert/svg-to-pdf for implementation details
    const response = await fetch('/api/convert/svg-to-pdf', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ 
        svg: svgData,
        format: options.format || 'A4',
        orientation: options.orientation || 'portrait',
        margin: options.margin || 20
      })
    });
    
    if (!response.ok) {
      throw new Error('PDF conversion failed: ' + response.statusText);
    }
    
    return await response.blob();
  }

  async convertSvgToVideo(svgData, options = {}) {
    // Integration with our SVG to Video converter
    // See: /tools/svg-to-video for animation capabilities
    const response = await fetch('/api/convert/svg-to-video', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ 
        svg: svgData,
        duration: options.duration || 3,
        fps: options.fps || 24,
        format: options.format || 'mp4',
        animation: options.animation || 'fadeIn'
      })
    });
    
    if (!response.ok) {
      throw new Error('Video conversion failed: ' + response.statusText);
    }
    
    return await response.blob();
  }

  getMetrics() {
    return {
      ...this.metrics,
      averageProcessingTime: this.metrics.conversions > 0 
        ? Math.round(this.metrics.totalProcessingTime / this.metrics.conversions)
        : 0,
      successRate: this.metrics.conversions > 0
        ? ((this.metrics.conversions - this.metrics.errors) / this.metrics.conversions * 100).toFixed(2)
        : 0
    };
  }
}

Performance Optimization & Best Practices

Memory Management

/**
 * Memory-efficient batch processing
 */
class BatchHtmlToSvgProcessor {
  constructor(concurrencyLimit = 3) {
    this.concurrencyLimit = concurrencyLimit;
    this.activeProcesses = 0;
    this.queue = [];
  }

  async processBatch(htmlDocuments) {
    const results = [];
    
    for (const doc of htmlDocuments) {
      if (this.activeProcesses >= this.concurrencyLimit) {
        await this.waitForSlot();
      }
      
      this.activeProcesses++;
      
      // Process with memory cleanup
      const processPromise = this.processWithCleanup(doc)
        .finally(() => {
          this.activeProcesses--;
          this.processQueue();
        });
      
      results.push(processPromise);
    }
    
    return Promise.all(results);
  }

  async processWithCleanup(htmlContent) {
    const converter = new Html2CanvasSvgConverter();
    
    try {
      return await converter.convertWithCanvas(htmlContent);
    } finally {
      // Force garbage collection if available
      if (window.gc) {
        window.gc();
      }
    }
  }

  async waitForSlot() {
    return new Promise(resolve => {
      this.queue.push(resolve);
    });
  }

  processQueue() {
    if (this.queue.length > 0 && this.activeProcesses < this.concurrencyLimit) {
      const resolve = this.queue.shift();
      resolve();
    }
  }
}

Error Handling & Fallback Strategies

/**
 * Robust error handling with automatic fallbacks
 */
class RobustHtmlToSvgConverter {
  constructor() {
    this.fallbackChain = [
      'html2canvas',
      'foreignObject',
      'serverSide'
    ];
  }

  async convertWithFallback(htmlContent, options = {}) {
    const errors = [];
    
    for (const method of this.fallbackChain) {
      try {
        switch (method) {
          case 'html2canvas':
            return await this.tryHtml2Canvas(htmlContent, options);
          
          case 'foreignObject':
            return await this.tryForeignObject(htmlContent, options);
          
          case 'serverSide':
            return await this.tryServerSide(htmlContent, options);
        }
      } catch (error) {
        errors.push({ method, error: error.message });
        console.warn(method + ' conversion failed:', error.message);
      }
    }
    
    // All methods failed
    throw new Error('All conversion methods failed: ' + JSON.stringify(errors));
  }

  async tryServerSide(htmlContent, options) {
    // Fallback to server-side conversion API
    const response = await fetch('/api/convert/html-to-svg', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ html: htmlContent, options })
    });
    
    if (!response.ok) {
      throw new Error('Server conversion failed: ' + response.statusText);
    }
    
    return await response.text();
  }
}

Testing & Validation

Comprehensive Test Suite

/**
 * Production testing patterns for HTML to SVG conversion
 */
class HtmlToSvgTester {
  constructor() {
    this.testCases = [
      {
        name: 'Basic HTML',
        html: '<h1>Test</h1>',
        expected: { width: 400, height: 200 }
      },
      {
        name: 'CSS Styled Content',
        html: '<div style="color: red; font-size: 24px;">Styled</div>',
        expected: { width: 600, height: 300 }
      },
      {
        name: 'Complex Layout',
        html: `
          <div style="display: flex; padding: 20px;">
            <div style="flex: 1; background: blue; color: white;">Left</div>
            <div style="flex: 2; background: green; color: white;">Right</div>
          </div>
        `,
        expected: { width: 800, height: 400 }
      }
    ];
  }

  async runTests() {
    const converter = new Html2CanvasSvgConverter();
    const results = [];
    
    for (const testCase of this.testCases) {
      try {
        const startTime = performance.now();
        const result = await converter.convertWithCanvas(
          testCase.html,
          testCase.expected
        );
        const duration = performance.now() - startTime;
        
        // Validate SVG output
        const isValid = this.validateSvgOutput(result);
        
        results.push({
          name: testCase.name,
          success: isValid,
          duration: duration.toFixed(2) + 'ms',
          size: (result.length / 1024).toFixed(2) + 'KB'
        });
        
      } catch (error) {
        results.push({
          name: testCase.name,
          success: false,
          error: error.message
        });
      }
    }
    
    return results;
  }

  validateSvgOutput(svgString) {
    // Basic SVG validation
    return svgString.includes('<svg') && 
           svgString.includes('</svg>') &&
           svgString.includes('xmlns="http://www.w3.org/2000/svg"');
  }
}

// Run tests in development
if (process.env.NODE_ENV === 'development') {
  const tester = new HtmlToSvgTester();
  tester.runTests().then(results => {
    console.table(results);
  });
}

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• SVG Converter API Documentation: Server-side integration

Conclusion: Production-Ready HTML to SVG Conversion

1. Use foreignObject for simple, styled HTML with excellent performance
2. Choose html2canvas for complex layouts requiring pixel-perfect rendering
3. Implement proper error handling with fallback strategies
4. Optimize for memory usage in batch processing scenarios
5. Test comprehensively across different HTML structures and CSS patterns

The techniques covered here integrate seamlessly with our complete converter ecosystem, enabling powerful multi-format workflows for any development project.

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