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Web Workers for Parsing Raw Input in Chrome Packaged Calculator App

I am currently working on a calculator that will run as a packaged (desktop) chrome app. I am using the math.js library to parse math input. This is my old code:
evaluate.js:
var parser = math.parser();
function evaluate(input){
$("#output").text(parser.eval(input));
}
However, if the input is something unreasonable like 6234523412368492857483928!, the app just freezes, because it is trying to evaluate the input. I know that math.js is still in beta so eventually there might be a fix (overflow errors), but I couldn't find any other library that parses raw input the way math.js does.
To fix this, I am trying to fix this using web workers to run it asynchronously. Here is the code that I have right now:
main.js
var evaluator = new Worker('evaluate.js');
evaluator.addEventListener('message', function(e){
$("#output").text(e.data);
}, false);
function evaluate(input){
evaluator.postMessage(input);
}
evaluate.js
var parser = math.parser();
function mathEval(input){
return parser.eval(input);
}
self.addEventListener('message', function(e){
self.postMessage(mathEval(e.data));
});
However, this doesn't work when I run it. Also, I noticed that when I use web workers, it throws the error Uncaught ReferenceError: math is not defined - evaluate.js:1, but it didn't throw this error with the old code.
Questions: Why doesn't this code work to evaluate the input? Is it possible to use multiple workers to speed it up? If I wanted to implement some sort of overflow error for when the worker takes more than 2 seconds, what would be the best way to go about doing it? Finally, is there a better way to do this?

Web Workers are run in totally separate context. They don't have access to the objects from parent web page. If you want to use math.js you have to import it into the worker using importScript.
I recommend to read Using Web Workers guide, part "Importing Scripts And Libraries" which describes how to do it, and how it works in detail.

jQuery on MTurk, why does Chrome report "Unsafe JavaScript attempt to access frame with URL"?

I'm doing a couple of things with jQuery in an MTurk HIT, and I'm guessing one of these is the culprit. I have no need to access the surrounding document from the iframe, so if I am, I'd like to know where that's happening and how to stop it!
Otherwise, MTurk may be doing something incorrect (they use the 5-character token & to separate URL arguments in the iframe URL, for example, so they DEFINITELY do incorrect things).
Here are the snippets that might be causing the problem. All of this is from within an iframe that's embedded in the MTurk HIT** (and related) page(s):
I'm embedding my JS in a $(window).load(). As I understand it, I need to use this instead of $(document).ready() because the latter won't wait for my iframe to load. Please correct me if I'm wrong.
I'm also running a RegExp.exec on window.location.href to extract the workerId.
I apologize in advance if this is a duplicate. Indeed - after writing this, SO seems to have a made a good guess at this: Debugging "unsafe javascript attempt to access frame with URL ... ". I'll answer this question if I figure it out before you do.
It'd be great to get a good high-level reference on where to learn about this kind of thing. It doesn't fit naturally into any topic that I know - maybe learn about cross-site scripting so I can avoid it?
** If you don't know, an MTurk HIT is the unit of work for folks doing tasks on MTurk. You can see what they look like pretty quick if you navigate to http://mturk.com and view a HIT.
I've traced the code to the following chunk run within jquery from the inject.js file:
try {
isHiddenIFrame = !isTopWindow && window.frameElement && window.frameElement.style.display === "none";
} catch(e) {}

I had a similar issue running jQuery in MechanicalTurk through Chrome.
The solution for me was to download the jQuery JS files I wanted, then upload them to the secure amazon S3 service.
Then, in my HIT, I called the .js files at their new home at https://s3.amazonaws.com.
Tips on how to make code 'secure' by chrome's standards are here:
http://developer.chrome.com/extensions/contentSecurityPolicy.html

This isn't a direct answer to your question, but our lab has been successful at circumventing (read hack) this problem by asking workers click on a button inside the iframe that opens a separate pop-up window. Within the pop-up window, you're free to use jQuery and any other standard JS resources you want without triggering any of AMT's security alarms. This method has the added benefit of allowing workers to view your task in a full-sized browser window instead of AMT's tiny embedded iframes.

Programatically retrieve count of javascript errors on page

I'd like to write a test case (using Selenium, but not the point of this question) to validate that my web application has no script errors\warnings or unhanded exceptions at certain points in time (like after initializing a major library).
This information can easily be seen in the debug consoles of most browsers. Is it possible to execute a javascript statement to get this information programatically?
It's okay if it's different for each browser, I can deal with that.

not so far read about your issue (as far as I understood your problem) here
The idea be the following:
I found, however, that I was often getting JavaScript errors when the page first loaded (because I was working on the JS and was introducing errors), so I was looking for a quick way to add an assert to my test to check whether any JS errors occurred. After some Googling I came to the conclusion that there is nothing built into Selenium to support this, but there are a number of hacks that can be used to accomplish it. I'm going to describe one of them here. Let me state again, for the record, that this is pretty hacky. I'd love to hear from others who may have better solutions.
I simply add a script to my page that will catch any JS errors by intercepting the window.onerror event:
<script type="text/javascript">
window.onerror=function(msg){
$("body").attr("JSError",msg);
}
</script>
This will cause an attribute called JSError with a value corresponding to the JavaScript error message to be added to the body tag of my document if a JavaScript error occurs. Note that I'm using jQuery to do this, so this specific example won't work if jQuery fails to load. Then, in my Selenium test, I just use the command assertElementNotPresent with a target of //body[#JSError]. Now, if any JavaScript errors occur on the page my test will fail and I'll know I have to address them first. If, for some strange reason, I want to check for a particular JavaScript error, I could use the assertElementPresent command with a target of //body[#JSError='the error message'].
Hope this fresh idea helps you :)

try {
//code
} catch(exception) {
//send ajax request: exception.message, exception.stack, etc.
}
More info - MDN Documentation

SoundManager2 SWF Load Issue

Trying to load Soundmanager2's SWF file from our CDN. I assume I'm running into cross domain flash issues. has anybody done this? it is even possible?
here's what I'm trying...
var allowxdomainscripting = true;
var xdomain = "*";
soundManager.url = 'http://cdn.mycompany.com/inc/soundmanager2.swf';
there's a very obscure reference to this in the documentation, but it's pretty vague...
http://www.schillmania.com/projects/soundmanager2/doc/generated/src/SoundManager2_AS3.html
any help is appreciated.

I ran into this as well at one point. SoundManager2 now comes with cross-domain versions of the swf files.
They are zipped up in swf/soundmanager2_flash_xdomain.zip
https://github.com/scottschiller/SoundManager2/tree/master/swf
Simply unzip and replace with the standard .swf files provided with SoundManager2 and your problem should go away.

THANK YOU VERY MUCH!
I stumbled upon this answer by total chance after wasting a couple of hours trying to get SM2 SWF embed to work.
I'm going to "revive" this to add a few keywords so Google indexes this answer... Maybe the next person trying to embed SoundManager2 SWF in a cross-domain environment gets it done a little quicker than I did :)
The error I was getting upon flash initialization was: Error calling method on NPObject
On the JS side, this was the code that broke everything:
// attempt to talk to Flash
flash._externalInterfaceTest(false); <- KABOOM!
NPObject errors might have many meanings, but more often than not (in our environment) it means: You're trying to call the ExternalInterface through JS on a flash movie hosted on a different domain.
After a while I popped open SoundManager2 ActionScript 3 code and saw this:
public var allow_xdomain_scripting:Boolean = false;
public var xdomain:String = "*";
[... other stuff ...]
if (allow_xdomain_scripting && xdomain) {
Security.allowDomain(xdomain);
version_as += ' - cross-domain enabled';
}
Of course that means that the movie that you might be using (no matter if it's debug or not) will not be accessible from a different domain (a CDN, or whatever).
The solution was –as stated in #amlutz160's answer– to use the files contained in swf/soundmanager2_flash_xdomain.zip, which are compiled with allow_xdomain_scripting = true.
Posting this is quite embarrassing, and the solution is obvious, but I lost quite a bit of time with this and AFAIK the contents of that mysterious zip file are not documented anywhere (I found a tangential mention on SM2 forums).
PS: I'm forwarding this answer to Scott Schiller so maybe he can update SoundManager2 docs a little bit :P
Regards!

printing out error messages in the javascript version of processing

To make a long story short I have to use processing in a class and I'm completely blind. The ide is completely inaccessible so I use the JavaScript version of processing to create a page and have a sited person describe the output to me. Unfortunately if the code has errors the page appears blank and there is no explanation of what’s wrong. Given the following code is there a way for the JavaScript version of processing to tell me that I have a syntax error since I forgot );
void setup()
{
size(500, 500);
}
void draw()
{
line(250, 200, 250, 40
}

Well for debuging (when the code compiles) you can use the println() command.
I've been using processing for 2 months now and i have the same problem and haven't been able to find a solution for it.
Here in SO for what I've seen almost no one uses Processing or knows how to use it. You can try the processing forums, you'll normally get an answer in a day or two. You can find that here http://processing.org/discourse/
Sorry for not being able to help. The other only solution I see is if you use their PDE (Processsing develop environment) and compile it there.
Edit: From previous experience asking processing questions you won't even have much ppl looking into your question :(

A js editor with syntax highlighting (such as Aptana) will show you errors such as you have there.
I don't know whether you'd find that any more useful than the Processing ide itself, though.

When you open the page in a browser, make sure you have the developer tools open. They come with every major browser (look in the tools menu), and include a JavaScript console. This will include any errors you get from the Processing.js parser.
I'm not sure if there are more accessible versions of the developer tools, but that would be a good place to start.

in processing.js, use createCanvas();
instead of size,
thus:
createCanvas(500, 500);