Export a string or an array to CSV [duplicate]

Question

I have a very simple array that I'd like to export to CSV:

var uniqueCounties = ["555","123","345"];

I have tried using methods found online but I have been getting various errors, and all the methods online deal with nested arrays.

My function at the moment is converting to a string. I was hoping it would simplify the process but I'm still now sure how to progress:

function download_csv() {
        var csv = uniqueCounties.toString();
        console.log(csv);
    }

I was originally trying this method:

uniqueCounties.forEach(function(infoArray, index){

   dataString = infoArray.join(",");
   csvContent += index < data.length ? dataString+ "\n" : dataString;

});

But kept getting the error infoArray.join is not a function.

Balázs Édes · Accepted Answer · 2017-03-30 16:52:27Z

2

If you have a 2d array of strings (or anything that you are ok with toString-ing) for example:

const input = [
  ["555","123","345"],
  [1, 2, 3],
  [true, false, "foo"]
]

Then you can do something like this:

function toCsv(input) {
  return input.map(row => row.join(',')).join('\n')
}

const csvString = toCsv(input)

Resulting in this string:

555,123,345
1,2,3
true,false,foo

If you just want to convert a single 1d array to csv, like in the example then:

const uniqueCounties = ["555","123","345"]

// If you want each value as a column
const csvAsSingleRow = uniqueCounties.join(',')

// If you want each value as a row
const csvAsSingleColumn = uniqueCounties.join('\n')

This gets more and more complicated if you want to include escaping, etc... In that case I'd recommend looking for a library that does this well.

edited Mar 30, 2017 at 16:52

answered Mar 30, 2017 at 16:43

Balázs Édes

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4 Comments

Matthew Snell Over a year ago

Thanks for the reply! I went with the csvAsSingleRow approach and had it console.log the output. Would it be difficult from here to download this as a CSV file?

Balázs Édes Over a year ago

Not sure what do you mean by download. Do you run this in the browser or node?

Matthew Snell Over a year ago

It's ran in the browser. The idea is someone can map counties (hence the uniqueCounties variable). And then export the selection to a file on their computer.

Balázs Édes Over a year ago

See this answer for that stackoverflow.com/a/14966131/1126273 You have to either encode it as an URI along with the information of what file type it is and call window.open with the string, or create a link. The answer explains both nicely.

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