CSV Transformation with node.js

Owned by Joël Gähwiler
Last updated: Nov 13, 2017

The node.js tool can be used to write a script that transforms a CSV file. To get started make sure you have node.js installed and know how to use the terminal.

Install Modules

You need to install the csv-parse and csv-stringify module to be able to turn a CSV file into a data structure and later create a CSV file from that data structure.

npm install csv-parse csv-stringify

Create Script

Create the following script in the same directory where you have installed the modules:

// require the filesystem module
var fs = require('fs');

// require csv modules
var parse = require('csv-parse/lib/sync');
var stringify = require('csv-stringify/lib/sync');

// read the file
var data = fs.readFileSync('data.csv');

// convert the data to a table
var table = parse(data, { delimiter: ';' });

// create a new table
var newTable = [];

// loop through the data
for(var i=0; i<table.length; i++) {
  // create a new row
  var newRow = [table[i][0], table[i][1] * 1000];

  // add the row to the new table
  newTable.push(newRow)
}

// generate csv data from the new table
var newData = stringify(newTable, { delimiter: ';' });
// console.log(newData);

// write file
fs.writeFileSync('data_new.csv', newData);

console.log('Yay!');

Run Script

Run the script as following to read the CSV and generate a new CSV:

node script.js