How to load file from inside Firefox plugin

Question

I'm working on a Firefox plugin which contains a file holding some HTML data. How do I load in this file as a string?

I can do

var contents = Components.utils.import("resource://stuff.html");

but that then tries to execute the XML file as Javascript. I just want its contents!

Answer 1

Using this function you can read files withing chrome scope.

function Read(file)
{
    var ioService=Components.classes["@mozilla.org/network/io-service;1"]
        .getService(Components.interfaces.nsIIOService);
    var scriptableStream=Components
        .classes["@mozilla.org/scriptableinputstream;1"]
        .getService(Components.interfaces.nsIScriptableInputStream);

    var channel=ioService.newChannel(file,null,null);
    var input=channel.open();
    scriptableStream.init(input);
    var str=scriptableStream.read(input.available());
    scriptableStream.close();
    input.close();
    return str;
}

var contents = Read("chrome://yourplugin/stuff.html");

Example loading CSS content and injecting on a page.

EDIT:

Just to update this because it is kinda handy !

let { Cc, Ci } = require('chrome');
function read(file){
    var ioService = Cc["@mozilla.org/network/io-service;1"]
        .getService(Ci.nsIIOService);
    var scriptableStream = Cc["@mozilla.org/scriptableinputstream;1"]
        .getService(Ci.nsIScriptableInputStream);

    var channel = ioService.newChannel2(file, null, null, null, null, null, null, null);
    var input = channel.open();
    scriptableStream.init(input);
    var str = scriptableStream.read(input.available());

    scriptableStream.close();
    input.close();
    return str;
}

Answer 2

For filesystem interactions in Firefox, use Mozilla XPCOM components. There are some wrappers for I/O XPCOM components such as JSLib and io.js

Using io.js it'd be something like:

var file = DirIO.get("ProfD"); // Will get you profile directory
file.append("extensions"); // extensions subfolder of profile directory
file.append("{1234567E-12D1-4AFD-9480-FD321BEBD20D}"); // subfolder of your extension (that's your extension ID) of extensions directory
// append another subfolder here if your stuff.xml isn't right in extension dir
file.append("stuff.xml");
var fileContents = FileIO.read(file);
var domParser = new DOMParser();
var dom = domParser.parseFromString(fileContents, "text/xml");
// print the name of the root element or error message
dump(dom.documentElement.nodeName == "parsererror" ? "error while parsing" : dom.documentElement.nodeName);