How to read CSV file in Javascript

Question

I need my code to be able to take data from a csv file and print it to the screen. At the moment it takes data from a txt file fine but a CSV will just return "file not supported". Here is my code.

<html>
<div id="page-wrapper">

        <div>
            Select a text file: 
            <input type="file" id="fileInput">
        </div>
        <pre id="fileDisplayArea"><pre>

    </div>
    <button onClick="test()">Show Text</button>
<script>
function test (){
    var file = fileInput.files[0];
var textType = /text.*/;
    if (file.type.match(textType)) {
  var reader = new FileReader();

  reader.onload = function(e) {
    var look = reader.result;
    window.alert (look);
  }

  reader.readAsText(file);  
} else {
  fileDisplayArea.innerText = "File not supported!";
}
}


</script>

Dekel · Accepted Answer · 2016-10-31 12:40:07Z

2

The type property of the file object is the type that the OS provides, based on the extension of the file.

On windows, the filetype of csv files is application/vnd.ms-excel, so when you check:

file.type.match(/text.*/)

It's false.

You can use change your code to check for any of text.* or application/vnd.ms-excel:

var textType = /text.*/;
var csvType = 'application/vnd.ms-excel';
if (file.type.match(textType) || file.type == csvType) {

Another option is to check the extension of the file:

if (file.name.endsWith('.csv')) {
    ...
}

answered Oct 31, 2016 at 12:40

Dekel

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