agentsqripts/lib/performance/repeatedDomQueryDetector.js

Comprehensive static code analysis toolkit for identifying technical debt, security vulnerabilities, performance issues, and code quality problems

/**
 * @file Repeated DOM query detector
 * @description Detects repeated DOM queries that could be cached
 */

/**
 * Detects repeated DOM queries
 * @param {string} content - File content
 * @param {string} filePath - Path to the file
 * @returns {Array} Array of repeated DOM query issues
 */
function detectRepeatedDomQueries(content, filePath) {
  const issues = [];
  const lines = content.split('\n');
  const { PERFORMANCE_PATTERNS } = require('./performancePatterns');
  
  // Track DOM queries
  const queryMap = new Map();
  
  lines.forEach((line, index) => {
    const lineNumber = index + 1;
    
    // DOM query patterns
    const domPatterns = [
      { pattern: /document\.getElementById\s*\(['"`]([^'"`]+)['"`]\)/, type: 'getElementById' },
      { pattern: /document\.getElementsByClassName\s*\(['"`]([^'"`]+)['"`]\)/, type: 'getElementsByClassName' },
      { pattern: /document\.querySelector\s*\(['"`]([^'"`]+)['"`]\)/, type: 'querySelector' },
      { pattern: /document\.querySelectorAll\s*\(['"`]([^'"`]+)['"`]\)/, type: 'querySelectorAll' },
      { pattern: /\$\s*\(['"`]([^'"`]+)['"`]\)/, type: 'jQuery' },
      { pattern: /jQuery\s*\(['"`]([^'"`]+)['"`]\)/, type: 'jQuery' }
    ];
    
    domPatterns.forEach(({ pattern, type }) => {
      const match = line.match(pattern);
      if (match) {
        const selector = match[1];
        const key = `${type}:${selector}`;
        
        if (!queryMap.has(key)) {
          queryMap.set(key, []);
        }
        
        queryMap.get(key).push({ lineNumber, code: line.trim() });
      }
    });
  });
  
  // Find repeated queries
  queryMap.forEach((occurrences, key) => {
    if (occurrences.length > 1) {
      const pattern = PERFORMANCE_PATTERNS['repeated_dom_query'];
      const [type, selector] = key.split(':');
      
      // Check if queries are in the same function scope (within ~20 lines)
      for (let i = 0; i < occurrences.length - 1; i++) {
        for (let j = i + 1; j < occurrences.length; j++) {
          if (Math.abs(occurrences[i].lineNumber - occurrences[j].lineNumber) <= 20) {
            issues.push({
              type: 'repeated_dom_query',
              severity: pattern.severity,
              category: pattern.category,
              location: `${filePath}:${occurrences[i].lineNumber},${occurrences[j].lineNumber}`,
              line: occurrences[i].lineNumber,
              selector: selector,
              queryType: type,
              code: occurrences[i].code,
              description: `DOM query for "${selector}" repeated ${occurrences.length} times`,
              summary: `Repeated DOM query for "${selector}"`,
              recommendation: 'Cache DOM query result in a variable to avoid repeated lookups',
              effort: pattern.effort,
              impact: pattern.impact,
              estimatedSavings: '30-60% DOM performance improvement'
            });
            break; // Only report once per selector
          }
        }
      }
    }
  });
  
  return issues;
}

module.exports = {
  detectRepeatedDomQueries
};