Read a file in same directory as the JavaScript file

Question

I can load an image file located in the same relative path as the JavaScript file

var imgObj = new Image(); 
imgObj.src = "images/backdropLevel0.jpg";

But how do I do the same (as simply and with pure JavaScript) for a text file ?
(it has some initial data for a webGL game I am working on).

PS. I am not asking about user input from the client's computer using the new File object.

Answer 1

Fetching an image is easy since the browser takes care of all the fetching and rendering. However, loading an arbitrary file into your script requires a couple more lines:

var req = new XMLHttpRequest();
req.onload = function(){
    process_webgl_data(this.responseText);
};
req.open('GET', './webgl_init.dat');
req.send();

Where process_webgl_data is whatever you want to do with the text of the file.

EDIT: Two quick things. Remember that request URIs are resolved with respect to the html file rather than the script, and second, here's the documentation for XHR.