how to access a file on the client's machine

Question

I have a few clients that will be using my website, and I want each client to have their own "config" file (EX: location=1 for one computer, location=2 for another). I want to do this using a file I place on the client's machine and then when they access the website the client looks on their own machine and figures out what to load based on what's in that file. This file can be a CSV file, plain text file, or any other kind of file that it needs to be for this to work.

Looking online all I've seen is stuff with file uploader. I don't want them to have to select the file, just have the file contents load and call a javascript function when they do.

Example of file

Location=1
AnswerToQuestion=42

and another file

Location=2
AnswerToQuestion=15

and my JS function

var setAnswerToQuestion = function(answer){
  locationConfig.setAnswer(answer)
}

Answer 1

Take a look at localstorage. It's a persistent key/value system that the browser implements to keep data for your website/webapp.

The Basic Principle:

To set a variable:

localStorage.setItem('answer_1', '42');

To get a variable:

localStorage.getItem("answer_1");

I guess if you have lots of answers you would end up with an array/object something like this:

var answers = [42, 15];

Towards a Solution:

You could store and retrieve that by using JSON.stringify

localStorage.setItem('answers', JSON.stringify(answers));

var answers = JSON.stringify(localStorage.getItem('answers'));

Be Educated

Smashing Magazine has a tutorial here
Dive into HTML5 has a tutorial here

Answer 2

You can't access files on local machines without using "file upload". You could store your config files on browser localstorage as:

var getConfigData = function() {
    return JSON.parse(localStorage.getItem('config'));
}

var saveConfigData = function(config) {
    localStorage.setItem('config', JSON.stringify(config));
}

var addDataToConfig = function(key, value) {
    var config = getConfigData();
    config[key] = value;
    saveConfigData(config);
}

var config = {
    Location: 1,
    AnswerToQuestion: 42
};

// save new config
saveConfigData(config);

// add new data to config
addDataToConfig('name', 'John Doe');