This is a common error in Firefox. It is logged in console when you try to call on non existent DOM API method. Seeing this error message is very common with methods call to alert(), confirm(), drawImage() (canvas) and window.open(). You may think "how those methods could be 'non-existent'?", since they are standard APIs of the window object. Well, that's true, they can't, but consider the case when browser blocks your alert or pop-up windows. Firefox pop-up blocker will make those methods not available in that context and should silently carry on with the next statement, but instead it throws an error.

To solve this problem:

• make sure you are calling methods on non-null objects;
• remove alert(), confirm() or open() methods in unload event handler. FF pop-up blocker ignores all window.open() methods in the unload handler.

The flavours of the error message:

• NS_ERROR_NOT_AVAILABLE: Component returned failure code: 0x80040111 (NS_ERROR_NOT_AVAILABLE) [nsIDOMWindow.alert]
• NS_ERROR_NOT_AVAILABLE: Component returned failure code: 0x80040111 (NS_ERROR_NOT_AVAILABLE) [nsIDOMWindow.confirm]
• NS_ERROR_NOT_AVAILABLE: Component returned failure code: 0x80040111 (NS_ERROR_NOT_AVAILABLE) [nsIDOMCanvasRenderingContext2D.drawImage]

At the time of writing the problem has not been fixed.

We all use Firebug and sometimes need jQuery in pages that don’t already have it. In such cases you can use the following javascript code or the bookmarklet that would insert jQuery into the page’s DOM on the fly. Thus making jQuery available for use in Firebug.

Load jQuery to Firebug

Here are two options to jQuerify any page. The code is taken from a jQuerify javascript code snippet by John Resig.

Method 1: You can run this code to make jQuery available in Firebug:

var s = document.createElement('script');
s.setAttribute('src', 'http://ajax.googleapis.com/ajax/libs/jquery/1.3.1/jquery.min.js');
document.body.appendChild(s);
s.onload=function(){
    /*Your Code Here*/
};
void(s);

Method 2: Or you can drag this bookmarklet to your browser’s bookmarks toolbar:

• Load jQuery – When you click on this link it will load jQuery from Google’s server and make it available in Mozilla add-on Firebug.

Sometimes after all day long coding your code becomes not so effective and your code (usually interface related) becomes slow. You have done so many changes and don't exactly know what slowing it down. In cases like this (and of course, plenty other cases) you can test your JavaScript code performance.  First of all, you need Firefox browser and Firebug web developers life saver plugin. I can not think of my web programming work without it.

Anyway, Firebug makes available console variable to your JavaScript page. Console can be used for logging or printing out debugging information to the Firebug console. Console also has one handy method for tracking time in milliseconds.

console.time('timerName');

// Your javascript code to test here 

console.timeEnd('timerName');

You can use this script to test your JavaScript code. timerName in the code can be any name for your timer. Don't forget to end your timer using the same name for timeEnd().

This post will discuss and provide several solutions to "Access to restricted URI denied" error. This error is thrown in Firefox browser, while making AJAX request that does not comply with the browser's security policies.

The error occurs when application tries to do an AJAX request that does not comply with the same-origin policy or tries to access a local resource (file on your hard drive with a path like file://c:/Users/etc.). To solve this problem you need to change the URI to your files so that it appears as if they were on the same domain as the page your AJAX script is calling it from.

Let's try to reproduce the error.

$(document).ready(function(){

  // Try to load content from the hard drive
  $.get('file:///Users/path-to/seed-data.js', function(data){
    console.log(data);
  });

  // Try to load content from another domain
  $.ajax({
    url: "http://www.google.com/some-file.html",
  }).done(function(data) {
    console.log(data);
  });

  // Try to load content from the same domain, but different protocol
  // Assume we are on http://www.example.com page and trying to access
  // page on the same secure domain "https"
  $.get('https://www.example.com/seed-data.js', function(data){
    console.log(data);
  });

});

The examples above will result in the following error in your JavaScript console.

Access to restricted URI denied" code: "1012
xhr.open(type, s.url, s.async);

Reasons

1. In the first example, the reason for the error is Firefox's security model that does not allow retrieving/accessing resources localhost resources.

2. In the second example, Firefox enforced "same origin" security policy that does not allow accessing resources from other domains (NOTE: www.example.com and example.com are considered two different domains as well).

3. In the third example, we tried to access resources using different protocol (https). Don't forget HTTP and HTTPS are two different protocols.

Solutions

In order to solve the "Access to restricted URI denied" error, you need to identify which of the reasons above is causing your script to throw an error and fix it with one of the solutions below.

1. First problem: Deploy files to a web server or alternatively run one locally (ex. XAMPP). Once deployed, access your page from your domain (http://www.your-domain.com/page.html or http://localhost:port/page.html).

2. To access resources from other domains you have to overcome the "same origin policy". This can be done by putting a simple proxy script on your own domain and it would appear as if you are fetching resources from your own domain. You can find description and an example proxy script in “Cross domain AJAX scripting” post.

3. The solution to the last method is usually easy. In most cases it is either putting or removing "s" to/from "http". But for cases when you have to grab content from URL using different protocol, your only solution is to use proxy script described in the second solution.

If this post does not cover your case please leave a comment with reproducable code or a link to fiddle page. If you found this post helpful, please share/like it.