Use javascript to open and parse a file without server

Question

Ok, I have a webpage that will run locally, every hour it needs to read a csv "output.csv" and put its contents into a table. The output.csv is generated from a local program automatically. The goal being an internal status board.

The only thing I can't seem to figure out is, without a server or xmlrequst how do I load a plaintext into javascript? (the rest of it should be easy)

This is the code that I've tried:

var reader = new FileReader();
reader.onload = function(event) {
    var contents = event.target.result;
    console.log("File contents: " + contents);
};

reader.onerror = function(event) {
    console.error("File could not be read! Code " + event.target.error.code);
};

reader.readAsText("output.csv");

EDIT:

I've read that using this option "--allow-file-access-from-files" will override the settings and allow me to read local files from chrome. I'm sure there is a way.

Can you use AJAX without a server and grabbing a local file, I thought not. If you could provide an example, maybe using jsfiddle, in the answer section, I'll mark it — triunenature
– triunenature, Commented Oct 7, 2014 at 11:25
use File or Blob objects to specify the file or data to read. — Grundy
– Grundy, Commented Oct 7, 2014 at 11:35
You cannot instantiate FileReader object directly (var reader = new FileReader()). FileReader objects are obtained indirectly: as a result of a user selecting or from a drag and drop operation — hindmost
– hindmost, Commented Oct 7, 2014 at 11:40
@hindmost why cannot instantiate FileReader? var reader = new FileReader() work ok — Grundy
– Grundy, Commented Oct 7, 2014 at 11:50

triunenature · Accepted Answer · 2014-10-07 12:16:32Z

3

Ok, I found an answer!

Javascript:

$(document).ready(function(){

    $.get("output.csv", function( my_var ) {
        alert(my_var)
    });

});

Chrome: "chrome.exe --user-data-dir=c:\temp --allow-file-access-from-files --incognito """ & currentDirectory & "index.html"""

answered Oct 7, 2014 at 12:16

triunenature

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Comments

Pio · Accepted Answer · 2014-10-07 11:34:02Z

1

The problem is, that you are running JavaScript, that is running in the browser and for security reasons it cannot access any file from your computer. So if you are willing to stick with JavaScript just start a server (e.g. SimpleHttpServer or Node.js) which will supply the file to your code.

Otherwise you will need to ask the user explicitly to "upload" your csv to the webpage - even though it is offline and living in his browser.

edited Oct 7, 2014 at 11:34

answered Oct 7, 2014 at 11:27

Pio

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2 Comments

triunenature Over a year ago

I can't start a server, as the machine is locked down. The user is me, but this thing needs to be done completely automated. It's a full screen application running on a large screen. It will be running for months at a time without me even touching it.

triunenature Over a year ago

The "Security Reasons" can and are disbled, "--allow-file-access-from-files", I have used this flag. Now with the security gone, how do I load the file?

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