CSV Export Best Practices

// Generate CSV export with best practices
class CSVExporter {
  constructor(data, options = {}) {
    this.data = data;
    this.options = {
      includeMetadata: true,
      utf8BOM: true,
      dateFormat: 'iso',
      ...options
    };
  }
  
  export() {
    const lines = [];
    
    // Add metadata as comments
    if (this.options.includeMetadata) {
      lines.push(`# Report: ${this.options.reportName || 'Data Export'}`);
      lines.push(`# Generated: ${new Date().toISOString()}`);
      lines.push(`# Total Records: ${this.data.length}`);
      lines.push('');
    }
    
    // Add headers
    if (this.data.length > 0) {
      const headers = Object.keys(this.data[0]);
      lines.push(headers.join(','));
      
      // Add data rows
      this.data.forEach(record => {
        const row = headers.map(header => {
          let value = record[header];
          
          // Format dates
          if (value instanceof Date) {
            value = value.toISOString();
          }
          
          // Escape CSV fields
          return this.escapeField(value);
        });
        lines.push(row.join(','));
      });
    }
    
    let csv = lines.join('\n');
    
    // Add UTF-8 BOM for Excel
    if (this.options.utf8BOM) {
      csv = '\uFEFF' + csv;
    }
    
    return csv;
  }
  
  escapeField(value) {
    const str = String(value ?? '');
    if (str.includes(',') || str.includes('"') || str.includes('\n')) {
      return '"' + str.replace(/"/g, '""') + '"';
    }
    return str;
  }
  
  download(filename) {
    const csv = this.export();
    const blob = new Blob([csv], { type: 'text/csv;charset=utf-8;' });
    const link = document.createElement('a');
    link.href = URL.createObjectURL(blob);
    link.download = filename;
    link.click();
  }
}

// Usage
const exporter = new CSVExporter(users, {
  reportName: 'Active Users Report',
  utf8BOM: true
});
exporter.download('users-export.csv');