How to parse a XML string in a Firefox addon using Add-on SDK - firefox-addon

Question

I am trying to create a FF AddOn that brings some XML data from a website. But I can't find a way to parse my RESPONSE. First I used DOMParser but I get this error:
ReferenceError: DOMParser is not defined.
Someone suggested to use XMLHttpRequest, because the parsing is done automatically but then I get this other error:
Error: An exception occurred. Traceback (most recent call last):
File
"resource://jid0-a23vmnhgidl8wlymvolsst4ca98-at-jetpack/api-utils/lib/cuddlefish.js",
line 208, in require
let module, manifest = this.manifest[base], requirer = this.modules[base]; TypeError: this.manifest is undefined
I really don't know what else to do. I must note that I am using the AddOn Builder to achieve this.
Below the code that doesn't seem to work.
Option 1:
exports.main = function() {
require("widget").Widget({
id: "widgetID1",
label: "My Mozilla Widget",
contentURL: "http://www.mozilla.org/favicon.ico",
onClick: function(event) {
var Request = require("request").Request;
var goblecontent = Request({
url: "http://www.myexperiment.org/search.xml?query=goble",
onComplete: function (response) {
var parser = new DOMParser();
var xml = parser.parseFromString(response.text, "application/xml");
var packs = xml.getElementsByTagName("packs");
console.log(packs);
}
});
goblecontent.get();
}
});
};
Option 2:
exports.main = function() {
require("widget").Widget({
id: "widgetID1",
label: "My Mozilla Widget",
contentURL: "http://www.mozilla.org/favicon.ico",
onClick: function(event) {
var request = new require("xhr").XMLHttpRequest();
request.open("GET", "http://www.myexperiment.org/search.xml?query=goble", false);
request.send(null);
if (request.status === 200) {
console.log(request.responseText);
}
}
});
};

Answer 1

DOMParser constructor isn't defined in the context of SDK modules. You can still get it using chrome authority however:
var {Cc, Ci} = require("chrome");
var parser = Cc["#mozilla.org/xmlextras/domparser;1"].createInstance(Ci.nsIDOMParser);
nsIDOMParser documentation.
That said, your approach with XMLHttpRequest should work as well. You used the new operator incorrectly however, the way you wrote it a new "require object" is being created. This way it should work however:
var {XMLHttpRequest} = require("xhr");
var request = new XMLHttpRequest();
Please consider using an asynchronous XMLHttpRequest object however, use request.onreadystatechange to attach your listener (the xhr module currently doesn't support other types of listeners or addEventListener).

Answer 2

If you use XMLHttpRequest (available via the xhr module) you can easily avoid the use of DOMParser. Bellow I provide an example supposing request is an XMLHttpRequest object which request is successfully completed:
Instead of:
var parser = new DOMParser();
var xmlDoc = parser.parseFromString(request.responseText, "application/xml");
Use:
var xmlDoc = request.responseXML;
An then you can:
var packs = xmlDoc.getElementsByTagName("packs");
console.log(packs);
Or whatever.