So, I might be a little late to the party, but this is to help anybody else who's been ripping his/her hair out looking for a solution to this.
First of all, CORS needs to be allowed in the browser if you're not running your HTML file off a server. Second, I found that the code snippets most people refer to in these kind of threads don't work for loading local XML-files. Try this (example taken from the official docs):
var xhr = new XMLHttpRequest();
xhr.open('GET', 'file.xml', true);
xhr.timeout = 2000; // time in milliseconds
xhr.onload = function () {
// Request finished. Do processing here.
var xmlDoc = this.responseXML; // <- Here's your XML file
};
xhr.ontimeout = function (e) {
// XMLHttpRequest timed out. Do something here.
};
xhr.send(null);
The method (1st arg) is ignored in xhr.open if you're referring to a local file, and async (3rd arg) is true by default, so you really just need to point to your file and then parse the result! =)
Good luck!