Promises usage

Starting with Node.js version 15, the Stream API promise a new "stream/promises" module.

Part of the Stream Promises module is the finished function. The Function plugs into a stream and resolves a promise when it is no longer readable, writable or has experienced an error or a premature close event.

The promises example leverages pipe as well as finished to provide a convenient solution to read a file from the file system and to pipe its output into the parser.

This example is available with the command node samples/recipe.promises.js.

import assert from "node:assert";
import fs from "node:fs";
import os from "node:os";
import { parse } from "csv-parse";
// Note, the `stream/promises` module is only available
// starting with Node.js version 16
import { finished } from "stream/promises";

  // Prepare the dataset
  await fs.promises.writeFile(
    `${os.tmpdir()}/input.csv`,
    ["a,b,c", "1,2,3"].join("\n"),
  );
  // Read and process the CSV file
  const processFile = async () => {
    const records = [];
    const parser = fs.createReadStream(`${os.tmpdir()}/input.csv`).pipe(
      parse({
        // CSV options if any
      }),
    );
    parser.on("readable", function () {
      let record;
      while ((record = parser.read()) !== null) {
        // Work with each record
        records.push(record);
      }
    });
    await finished(parser);
    return records;
  };
  // Parse the CSV content
  const records = await processFile();
  // Validate the records
  assert.deepStrictEqual(records, [
    ["a", "b", "c"],
    ["1", "2", "3"],
  ]);

./packages/csv-parse/samples/recipe.promises.js