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I have a Task.csv file with the following content:

task1,01/05/2020, 20/05/2020, Active
task2,03/05/2020, 17/05/2020, Active
task3,10/05/2020, 25/05/2020, Active
task4,02/05/2020, 21/05/2020, Active
task5,07/05/2020, 28/05/2020, Active

I want to parse this in JavaScript (NodeJS) and display each line read surrounded by brackets. The following is the code I'm using:

function readCsvFile()
{
    var fs = require('fs');
    var textByLine = fs.readFileSync('Tasks.csv').toString().split("\n");   
    var i;<br>

    for (i=0; i<textByLine.length; i++)
    {
        console.log("[" + textByLine[i] + "]");
    }
}

What I expect:

[task1,01/05/2020, 20/05/2020, Active]
[task2,03/05/2020, 17/05/2020, Active]
[task3,10/05/2020, 25/05/2020, Active]
[task4,02/05/2020, 21/05/2020, Active]
[task5,07/05/2020, 28/05/2020, Active]

When I run it, the output is:

]task1,01/05/2020, 20/05/2020, Active
]task2,03/05/2020, 17/05/2020, Active
]task3,10/05/2020, 25/05/2020, Active
]task4,02/05/2020, 21/05/2020, Active
[task5,07/05/2020, 28/05/2020, Active]

I'm new to JavaScript and NodeJS so any ment would be helpful, thanks.

I have a Task.csv file with the following content:

task1,01/05/2020, 20/05/2020, Active
task2,03/05/2020, 17/05/2020, Active
task3,10/05/2020, 25/05/2020, Active
task4,02/05/2020, 21/05/2020, Active
task5,07/05/2020, 28/05/2020, Active

I want to parse this in JavaScript (NodeJS) and display each line read surrounded by brackets. The following is the code I'm using:

function readCsvFile()
{
    var fs = require('fs');
    var textByLine = fs.readFileSync('Tasks.csv').toString().split("\n");   
    var i;<br>

    for (i=0; i<textByLine.length; i++)
    {
        console.log("[" + textByLine[i] + "]");
    }
}

What I expect:

[task1,01/05/2020, 20/05/2020, Active]
[task2,03/05/2020, 17/05/2020, Active]
[task3,10/05/2020, 25/05/2020, Active]
[task4,02/05/2020, 21/05/2020, Active]
[task5,07/05/2020, 28/05/2020, Active]

When I run it, the output is:

]task1,01/05/2020, 20/05/2020, Active
]task2,03/05/2020, 17/05/2020, Active
]task3,10/05/2020, 25/05/2020, Active
]task4,02/05/2020, 21/05/2020, Active
[task5,07/05/2020, 28/05/2020, Active]

I'm new to JavaScript and NodeJS so any ment would be helpful, thanks.

• javascript
• node.js
• csv
• parsing

Share Improve this question Follow edited Apr 18, 2020 at 16:06 Alessandro Candeloro 1,07166 silver badges2020 bronze badges asked Apr 18, 2020 at 11:27 Chich AronChich Aron 5111 gold badge11 silver badge22 bronze badges 1

• Note, if you wrote the csv file in Windows you are more than likely dealing with a CRLF(carriage return and line feed) line endings, eg \r\n instead of just \n. Check your text editor it might have a setting you can change to tell it to Use unix style line endings – Patrick Evans Commented Apr 18, 2020 at 11:37

Add a ment  | 

5 Answers 5

Sorted by: Reset to default 5

Do not read files synchronously. If you are reading big files you can use the built-in module readline to read a file line by line and process each line where you don't have to worry about CLRF. Alternatively using a module like fast-csv has many features.

fast-csv

const fs = require('fs');
const path = require('path');
const csv = require('fast-csv');

fs.createReadStream('Tasks.csv')
    .pipe(csv.parse({ headers: true }))
    .on('error', error => console.error(error))
    .on('data', row => console.log(row))
    .on('end', rowCount => console.log(`Parsed ${rowCount} rows`));

Readline

   const readline = require('readline');
    const fs = require('fs');
    
    cost lineReader = readline.createInterface({
      input: fs.createReadStream('Tasks.csv')
    });
    
    let lineno = 0;
    lineReader.on('line', function (line) {
         lineno++
       // process line here
       // let colValues=  line.split(",") 
    });
  
   lineReader.on('close', () => {
    console.log('Done reading file');
   });

Better syntax using for await loop

for await (let line of lineReader) {
       console.log(line);
      }
 

Please try like this

function readCsvFile()
{
    var fs = require("fs");
    var textByLine = fs.readFileSync("Tasks.csv").toString().split("\n");
    console.log(textByLine);
    const res = textByLine.map((line) => line.split(","));
    console.log(res)
}

output

[["task1","01/05/2020"," 20/05/2020"," Active\r"],
 ["task2","03/05/2020"," 17/05/2020"," Active\r"],
 ["task3","10/05/2020"," 25/05/2020"," Active\r"],
 ["task4","02/05/2020"," 21/05/2020"," Active\r"],
 ["task5","07/05/2020"," 28/05/2020"," Active"]]

To fix your code just use .split() method of Javascript to get the result in desired format. I have done a small change in your code and getting response the way you mentioned.

function readCsvFile() {
    var fs = require('fs');
    var textByLine = fs.readFileSync('data.csv').toString().split("\n");
    var i;
    for (i = 0; i < textByLine.length-1; i++) {
        console.log(textByLine[i].split("\t"))
    }
}

Thanks for your feedback everyone! It solved my problem. I tried @PatrickEvans suggestion first, and it worked! Basically I should be using "\r\n" to split the file into individual lines as I created the CSV file in Windows.

So now this is the working code

function readCsvFile()
{

    var fs = require('fs');
    var textByLine = fs.readFileSync('Tasks.csv').toString().split("\r\n"); 
    var i;

    for (i=0; i<textByLine.length; i++)
    {
        console.log("[" + textByLine[i] + "]");
    }
}

Although it can be problematic to import node.js modules for trivial purposes, the parsing of CSV files has enough edge cases and gotchas for it to be better done by one that's well tested. The top result on NPM is this: https://www.npmjs./package/csv-parser

Using a module will also reduce the amount of fiddly and fragile code you'll have to maintain yourself.

Here's a link to the RFC for CSV files, which is the closest thing I know of to a standard for them: https://www.rfc-editor/rfc/rfc4180 Hopefully this will give you enough info about the edge cases I mention to appreciate the need to use a module instead.

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