Parsing Data from a file Nodejs

Question

Just trying to experiment with node and lost on this one.

I am trying to read a file using node.js and sum the prices in that file.

So far I can read the data but am having problems adding just the prices.

const fs = require('fs')

fs.readFile('file.txt', 'utf8' , (err, data) => {
  if (err) {
    console.error(err)
    return
  }
  console.log(data)
})

in file.txt I have

"id,item,price 1,Milk,5 2,Soap,10 3,Water,2"

From the file.txt I only need to add the prices and print it out.

For example for above example, I would have "price = 17"

Any guidance in the right direction is appreciated

marc_s · Accepted Answer · 2021-06-24 18:24:18Z

1

Firstly, I assume that the file is a CSV, because of all the commas :).

You can easily parse CSV files with csv-parse.

We just need to additionally specify that the record_delimiter is a space (' '), not the standard new line ('\n')

const csv = require("csv-parse");
const fs = require('fs');
const res = [];

fs.createReadStream('test.txt')
    .pipe(csv({ record_delimiter: ' '})) // pipe input stream to the CSV parser

    .on('data', (data) => res.push(data)) // push data to the result array
    .on('end', () => {
        var price = 0; // create a variable for the price
        for(var s=1; s<res.length; s++) //  iterate over all records
            price += parseInt(res[s][2]);
        console.log(price); // print the price
    })
    .on('error', (err) => {
        console.log("error: " + err);
    });

We can also change it a bit so that we work with objects by setting columns to true (I find the data more sorted that way)

const csv = require("csv-parse");
const fs = require('fs');
const res = [];

fs.createReadStream('test.txt')
    .pipe(csv({ record_delimiter: ' ', columns: true})) // pipe input stream to the CSV parser

    .on('data', (data) => res.push(data)) // push data to the result array
    .on('end', () => {
        var price = 0; // create a variable for the price
        res.forEach(el => price += parseInt(el.price)) // Iterate on each object and get the price field
        console.log(price); // print the price
    })
    .on('error', (err) => {
        console.log("error: " + err);
    });

With this code the data looks like this:

[
  { id: '1', item: 'Milk', price: '5' },
  { id: '2', item: 'Soap', price: '10' },
  { id: '3', item: 'Water', price: '2' }
]

edited Jun 24, 2021 at 18:24

marc_s

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answered Mar 12, 2021 at 19:43

ELKozel

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2 Comments

Heniam Over a year ago

Not sure if the solution is correct as I am getting 0 and my file is .txt not .csv

ELKozel Over a year ago

Yeah, I just noticed that there are " at the start and end of the file, if you remove those, it should be fine. Also, it is not a problem that the extension is .txt and not .csv

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