example CSV transformation in Node.js

csv-processing.js

const fs = require('fs')
const csv = require('csv');

fs.createReadStream('data.csv')
  .pipe(csv.parse({columns: true}))
  .pipe(csv.transform((input) => {
    return Object.assign({}, input, {
      foo: input['foo'].toUpperCase()
    });
  }))
  .pipe(csv.stringify({header: true}))
  .pipe(fs.createWriteStream('./data-processed.csv'))
  .on('finish', () => {
    console.log('Done 🍻 ');
  });

For example:

const fs = require('fs')
const csv = require('csv');

const rows = [];

fs.createReadStream('upload_7_17.csv')
  .pipe(csv.parse({columns: true}))
  .pipe(csv.transform((input) => {
    rows.push({...input});
  }))
  .on('finish', () => {
    console.log(rows);
  });

Note that this requires the data to fit in memory, so it may not scale as well as streaming row by row.

How can i do async operation in transform ?

Hi sorry, I'm not involved with the csv package and can't provide support for it. This is just an example I've posted as a reference. Stack Overflow or the csv github repository may be better places to ask for support.