This script is for converting csv to json

csv_to_json.js

const fs = require("fs");
const { parse } = require("csv-parse"); 

async function csvToJson(inputFile, outputFile) {
  return new Promise((resolve, reject) => {
    console.log(`Converting ${inputFile} to JSON...`);

    if (!fs.existsSync(inputFile)) {
      return reject(new Error(`Input file ${inputFile} does not exist`));
    }

    const parser = parse({
      columns: true,
      skip_empty_lines: true,
      trim: true,
    });

    const input = fs.createReadStream(inputFile, { encoding: "utf-8" });
    const output = fs.createWriteStream(outputFile);

    output.write("[\n"); // start JSON array

    let first = true;
    let count = 0;
    let preview = [];

    parser.on("data", (row) => {
      // Clean row
      const cleanedRow = {};
      for (const key in row) {
        if (row[key]?.toString().trim()) {
          cleanedRow[key] = row[key];
        }
      }

      if (!first) output.write(",\n");
      output.write(JSON.stringify(cleanedRow, null, 2));

      first = false;
      count++;

      // keep first 3 records for preview
      if (preview.length < 3) preview.push(cleanedRow);
    });

    parser.on("end", () => {
      output.write("\n]\n"); // end JSON array
      output.end();
      console.log(`Successfully parsed ${count} records`);
      console.log(`JSON saved to ${outputFile}`);
      console.log("\nPreview of first 3 records:");
      preview.forEach((rec, i) => console.log(`Record ${i + 1}:`, rec));
      resolve();
    });

    parser.on("error", (err) => reject(err));

    input.pipe(parser);
  });
}

// CLI usage
if (require.main === module) {
  const args = process.argv.slice(2);

  if (args.length < 1) {
    console.log("Usage: node csv_to_json.js <input.csv> [output.json]");
    console.log("Example: node csv_to_json.js data.csv converted.json");
    process.exit(1);
  }

  const inputFile = args[0];
  const outputFile = args[1] || inputFile.replace(/\.csv$/i, ".json");

  csvToJson(inputFile, outputFile)
    .then(() => console.log("Conversion completed successfully!"))
    .catch((err) => {
      console.error("Conversion failed:", err.message);
      process.exit(1);
    });
}

module.exports = { csvToJson };