Zero dependency CSV parser in TypeScript with generics support

csv-parser.ts

type CSVRow<T> = Record<keyof T, string | number>;

// eslint-disable-next-line @typescript-eslint/no-explicit-any
class CSVParser<T = any> {
  private rows: CSVRow<T>[];
  private header: (keyof T)[];

  constructor(csvData: string) {
    this.rows = this.parseCSV(csvData);
    this.header = this.rows.length > 0 ? (Object.keys(this.rows[0]) as (keyof T)[]) : [];
  }

  private parseCSV(csvData: string): CSVRow<T>[] {
    const [header, ...rows] = csvData
      .split("\n")
      .map(row => row.split(",").map(cell => cell.trim()));

    return rows.map(row =>
      row.reduce((acc, cell, index) => {
        const columnName = header[index].trim() as keyof T;
        acc[columnName] = isNaN(Number(cell)) ? cell : Number(cell);
        return acc;
      }, {} as CSVRow<T>)
    );
  }

  private getColumnIndex(columnName: keyof T): number {
    return this.header.indexOf(columnName);
  }

  getValues<K extends keyof T>(columnName: K): T[K][] {
    const columnIndex = this.getColumnIndex(columnName);

    if (columnIndex === -1) {
      throw new Error(`Column ${String(columnName)} not found`);
    }

    return this.rows.map(row => row[columnName] as T[K]);
  }

  getRow(index: number): CSVRow<T> | undefined {
    return this.rows[index];
  }

  getColumnValues<K extends keyof T>(columnName: K): T[K][] {
    const columnIndex = this.getColumnIndex(columnName);

    if (columnIndex === -1) {
      throw new Error(`Column ${String(columnName)} not found`);
    }

    return this.rows.map(row => row[columnName] as T[K]);
  }

  getAllData(): CSVRow<T>[] {
    return this.rows;
  }
}

Example usage:

// Example usage:
interface Person {
  Name: string;
  Age: number;
  City: string;
}

const csvData = `Name, Age, City
John Doe, 30, New York
Jane Smith, 25, San Francisco
Bob Johnson, 35, Los Angeles
Alice Williams, 28, Chicago`;

try {
  const csv = new CSVParser<Person>(csvData);

  console.log(csv.getValues("Age")); // Output: [30, 25, 35, 28]
  console.log(csv.getRow(1)); // Output: { Name: 'Jane Smith', Age: 25, City: 'San Francisco' }
  console.log(csv.getColumnValues("City")); // Output: ['New York', 'San Francisco', 'Los Angeles', 'Chicago']
  console.log(csv.getAllData()); // Output: Array of all rows as objects
} catch (error) {
  console.error(error.message);
}