Read text file and create dynamic variables

Question

Read text file and create dynamic variables

Zambetti, Luigi (Cognizant) 82

Hello,
in my ASP.NET WebForms application I have a folder Scripts where there are
a JavaScript file and a TXT file.

This TXT file contains some values, that I can insert on it how I want.
For example, one value for row:

Value01
Value02
Value03
..

or in comma separated values:

Value01,Value02,Value03

Now my question is:

is it possible, in the JavaScript file, read this TXT file and create
as many variables as the values in the TXT file?

For example, in this case, something like this:

var myValue01 = Value01;
var myValue02 = Value02;
var myValue03 = Value03;

Thanks in advance for every idea.

Luis

AgaveJoe 30,126 Reputation points

2022-01-01T14:02:11.93+00:00

Use JSON format rather than a comma separated string. Then you can make a basic AJAX call to get the JSON object. Very simple.

Accepted answer

3 additional answers

Your answer

AgaveJoe 30,126 Reputation points

2022-01-01T14:02:11.93+00:00

Use JSON format rather than a comma separated string. Then you can make a basic AJAX call to get the JSON object. Very simple.

Answer 1

Again, it is much easier to store the values in JSON (JavaScript Object Notation) format rather than a CSV string. Then you can can simply make an AJAX call to fetch the values without needing to do any manual serialization.

Example using your requirement.

public partial class _default : System.Web.UI.Page
{
    public string Json { get; set; }
    protected void Page_Load(object sender, EventArgs e)
    {
        PopulateValuesFromFile();
    }

    protected void PopulateValuesFromFile()
    {
        List<string> Values = new List<string>();
        foreach (string line in System.IO.File.ReadLines(Server.MapPath("~/Javascript/values.txt")))
        {
            Values.AddRange(line.Split(','));
        }

        Json = Newtonsoft.Json.JsonConvert.SerializeObject(Values);
    }
}

Then within a script tag in the aspx page render the JavaScript.

var values = <%=Json %>;

Answer 2

AgaveJoe 30,126

Again, I would use JSON rather than splitting a CSV string. Keep in mind that AJAX (fetch) is asynchronous. The code must wait for the HTTP request to finish before accessing the values.

JSON file

[
  "Value01",
  "Value02",
  "Value03"
]

ASPX page using fetch within a script tag.

fetch('https://localhost:44362/javascript/values.json')
    .then(response => response.json())
    .then(data => {
        console.log(data);
    });

Answer 3

Ken Tucker 5,861

I would use a javascript array to store mulitiple values from a text file

https://www.w3schools.com/js/js_arrays.asp

Zambetti, Luigi (Cognizant) 82 Reputation points

2022-01-01T14:20:38.977+00:00

ok, but how can I read the text file an put in an array?

Answer 4

Bruce (SqlWork.com) 78,161 Volunteer Moderator

It matter little if you use an array or a mapped object. JavaScript can not read the text file. You have two options

1) the webpage reads the text file and writes dynamic JavaScript to the page, as suggested in the first answer.

2) the JavaScript makes an Ajax call to a page method that returns a json object, either a mapped object or array.

Zambetti, Luigi (Cognizant) 82 Reputation points

2022-01-01T18:13:49.65+00:00

Why JavaScript cannot read a TXT file?
Because is under an application pool?
AgaveJoe 30,126 Reputation points

2022-01-02T13:11:53.847+00:00

JavaScript runs in the browser not on the server where the file exists. The application pool is on the server as well.
Zambetti, Luigi (Cognizant) 82 Reputation points

2022-01-02T13:16:18.647+00:00

Thank you Joe. Now is clear.

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Read text file and create dynamic variables

3 additional answers

Your answer