CSV Field Escaping

// Escape CSV field
function escapeCsvField(field) {
  // Convert to string
  field = String(field);
  
  // If contains comma, quote, or newline, quote it
  if (field.includes(',') || field.includes('"') || field.includes('\n')) {
    // Double any existing quotes
    field = field.replace(/"/g, '""');
    // Wrap in quotes
    return `"${field}"`;
  }
  
  return field;
}

// Generate CSV row
function generateCsvRow(values) {
  return values.map(escapeCsvField).join(',');
}

// Generate complete CSV
function generateCsv(data, headers) {
  const rows = [
    generateCsvRow(headers),
    ...data.map(row => generateCsvRow(
      headers.map(h => row[h] ?? '')
    ))
  ];
  return rows.join('\n');
}

// Usage
const data = [
  { name: 'Smith, John', quote: 'He said "Hello"', age: 30 },
  { name: 'Doe, Jane', quote: 'Simple text', age: 25 }
];

const csv = generateCsv(data, ['name', 'quote', 'age']);
console.log(csv);
// name,quote,age
// "Smith, John","He said ""Hello""",30
// "Doe, Jane",Simple text,25

// Parse CSV (basic)
function parseCsvRow(row) {
  const values = [];
  let current = '';
  let inQuotes = false;
  
  for (let i = 0; i < row.length; i++) {
    const char = row[i];
    const next = row[i + 1];
    
    if (char === '"' && inQuotes && next === '"') {
      current += '"';
      i++; // Skip next quote
    } else if (char === '"') {
      inQuotes = !inQuotes;
    } else if (char === ',' && !inQuotes) {
      values.push(current);
      current = '';
    } else {
      current += char;
    }
  }
  
  values.push(current);
  return values;
}

// Better: Use a library
// npm install papaparse
import Papa from 'papaparse';

const csv = Papa.unparse(data);
const parsed = Papa.parse(csv, { header: true });

import csv
import io

# Escape CSV field (manual)
def escape_csv_field(field):
    field = str(field)
    if ',' in field or '"' in field or '\n' in field:
        field = field.replace('"', '""')
        return f'"{field}"'
    return field

# Write CSV (recommended way)
def write_csv(data, headers):
    output = io.StringIO()
    writer = csv.DictWriter(output, fieldnames=headers)
    
    writer.writeheader()
    writer.writerows(data)
    
    return output.getvalue()

# Usage
data = [
    {'name': 'Smith, John', 'quote': 'He said "Hello"', 'age': 30},
    {'name': 'Doe, Jane', 'quote': 'Simple text', 'age': 25}
]

csv_content = write_csv(data, ['name', 'quote', 'age'])
print(csv_content)

# Read CSV
def read_csv(csv_string):
    input_stream = io.StringIO(csv_string)
    reader = csv.DictReader(input_stream)
    return list(reader)

# Custom delimiter/quoting
with open('output.csv', 'w', newline='') as f:
    writer = csv.writer(
        f,
        delimiter=',',
        quotechar='"',
        quoting=csv.QUOTE_MINIMAL  # Only quote when needed
    )
    writer.writerow(['Name', 'Quote', 'Age'])
    writer.writerow(['Smith, John', 'He said "Hello"', 30])