Read CSV Files In NodeJS (Very Simple Examples)

Welcome to a quick tutorial on how to read CSV files in NodeJS. Need to read some data from a CSV file in Node? Well, it is a piece of cake.

That covers the basics, but read on for more examples!

 

 

TLDR – QUICK SLIDES

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TABLE OF CONTENTS

 

 

 

EXAMPLE 1) READ CSV INTO AN OBJECT

1A) DUMMY CSV

Animal,Description
Doge,Good Boy
Cate,Evil
Birb,Happy Wings

For this example, we will be using a list of meme animals – The first row is the header.

 

1B) CSV PARSER INTO OBJECT

// (A) LOAD REQUIRED MODULES
// npm install csv-parser
// https://www.npmjs.com/package/csv-parser
const fs = require("fs"),
      csv = require("csv-parser");
 
// (B) READ CSV FILE
var results = [];
fs.createReadStream("1a-dummy.csv")
.pipe(csv())
.on("data", data => results.push(data))
.on("end", () => console.log(results));

[
  { Animal: 'Doge', Description: 'Good Boy' },
  { Animal: 'Cate', Description: 'Evil' },
  { Animal: 'Birb', Description: 'Happy Wings' }
]

Don’t think this needs a lot of explanation.

1. Load the required modules – The file system and CSV parser.
2. Open the dummy CSV file, pipe it to the CSV parser, and read it into an object. CSV parser will automatically use the first row as the object keys – [{ HEAD : VALUE }, { HEAD : VALUE }, ...]

 

 

EXAMPLE 2) READ CSV INTO AN ARRAY

2A) DUMMY CSV

Apple,Banana
Cherry,Durian
Elderberry,Fig

For this example, we have a different example CSV – Take note that there are no headers. Only a list of fruits.

 

2B) CSV PARSER INTO NUMERIC INDEXED OBJECT

// (A) LOAD REQUIRED MODULES
// npm install csv-parser
// https://www.npmjs.com/package/csv-parser
const fs = require("fs"),
      csv = require("csv-parser");
 
// (B) READ CSV FILE
var results = [];
fs.createReadStream("2a-dummy.csv")
.pipe(csv({ headers : false }))
.on("data", data => results.push(data))
.on("end", () => console.log(results));

[
  { '0': 'Apple', '1': 'Banana' },
  { '0': 'Cherry', '1': 'Durian' },
  { '0': 'Elderberry', '1': 'Fig' }
]

The only difference here is csv({ headers : false }), we tell the CSV parser that the first row is not a header. But take note, CSV parser now returns a number indexed object instead.

 

2C) CSV PARSER INTO ARRAY

// (A) LOAD REQUIRED MODULES
// npm install csv-parser
// https://www.npmjs.com/package/csv-parser
const fs = require("fs"),
      csv = require("csv-parser");
 
// (B) READ CSV FILE
var results = [];
fs.createReadStream("2a-dummy.csv")
.pipe(csv({ headers : false }))
.on("data", data => results.push(Object.values(data)))
.on("end", () => console.log(results));

[
  [ 'Apple', 'Banana' ],
  [ 'Cherry', 'Durian' ],
  [ 'Elderberry', 'Fig' ]
]

If you want to read the CSV file as a “flat array”, we simply have to do a bit of “data yoga” – Object.values(data) will do the trick.

 

 

 

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EXAMPLE CODE DOWNLOAD

Click here for the source code on GitHub gist, just click on “download zip” or do a git clone. I have released it under the MIT license, so feel free to build on top of it or use it in your own project.

 

 

LINKS & REFERENCES

• How To Read Files In NodeJS – Code Boxx
• How To Write CSV Files In NodeJS – Code Boxx
• CSV Parser – NPMJS

 

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