Exporting CSV File (spreadsheet) with JavaScript

I was working on a project where I needed to export a CSV (Comma Separated Values) file using JavaScript. I was feeling lazy and I thought I could find a nice Node package that would do most of the work for me. All the Node packages I found seemed very powerful, with lots of options, however it also appeared that they would be hard to figure out.

The problem with using a Node package or say a gem in ruby that is very powerful is that if they do not do exactly what you want, then you can spend hours if not days trying to figure out how to make them work for you. As a result, I made up my mind that it would be easier to just write the code myself.

I had data that looked like this on my web app:

(No these are not my Bitcoin address – lol, this from a list of the richest Bitcoin address)

And I wanted it to put out something that looked like this, when open by a spreadsheet:

(Screenshots from my app CryptoChecker – https://www.1337ipjbp7u9mi9cdlngl3g5napum7twzm.com)

In my case, I had the data I wanted to put out to a CSV file in an Array of Objects. Because the app is javascript, if the user closes the app all the data is lost. The public addresses are quite long and can be a pain to put into the app, so the user may want to store this information.

I had written similar code in React, Jquery and had done some CSV work in Ruby. So I put my nose to the grindstone and dug into writing the code. I quickly realized that the file management tool was going to be the key issue. In Ruby there are some excellent file management tools, however this is less true in Java Script.

Despite this I found a nice Node module, FileSaver.js (click here for FileSaver npm page), that would save the output file as a CSV and allows the user to name their file easily. After installing the FileSaver node module and importing it, the key line of code is:

var blob = new Blob([csv], {type: "text/plain;charset=utf-8"});
  saveAs(blob, "yourcsv.csv");

A Blob is just a chunk of data and the name comes from SQL databases and means “Binary Large Object”. As you can see you can name the file (yourcsv.csv) and determine the file type. Once I got this working, then I just need to get my Array of Objects into the right format.

I rewrote my actual code to make this post more clear for the reader. I start with a simple Array of Objects:

const arrayOfObjects = [{column1: "1", column2: "2", column3: "3"},{column1: 4, column2: 5, column3: 6}]

From here the code is fairly straight forward to convert the arrayOfObjects to a csv:

arrayOfObjects.map((row) => {
csv += `\r\n ${row.column1}, ${row.column2}, ${row.column3}`
})

Note the \r\n is a carriage return + line feed. This starts a new row. If you console log the csv, you get (if you add the keys as the headers).

column1, column2, column3, 
1, 2, 3
4, 5, 6

`
This is exactly what I wanted.

FileSaver.js worked perfectly and downloaded the file yourcsv.csv.

Here is the github gist (https://gist.github.com/1337ipJbP7U9mi9cdLngL3g5Napum7tWzM/fd9b8aafbba79dc76971e892c2c82ec0) of the code.

In order to provide you the code in a format you could easily play with, I had the bright idea to just put this example code in some script tags inside a web page and then to run it locally in Chrome browser (note ctr O allows you to open a local file). Unfortunately, this made it hard to work with the FileSaver.js Node module. You cannot use “Import” inside of script tags.

As a result, I had to go to the github page for FileSaver.js (https://github.com/eligrey/FileSaver.js), copy the “FileSaver.js” file in the “dist” folder and paste it into a new file in the same directory as my code. The FileSaver.js is then imported using a “script src=” tag on line 6, as seen below

<script src="./filesaver.js"></script>

You will need to do this also if you want to play with the code.

There may be a better way to put out a CSV file, however it is good enough for an Indie Hacker. If you know a better way, let me know in the comments.