We Keep Coding

executing javascript through url

I'm trying to set the value of a textarea on the following page by executing something similar the below javascript:
javascript:alert(document.getElementsByClassName('uiTextareaNoResize uiTextareaAutogrow _1rv DOMControl_placeholder')[0].value='blabla');
This works if I manually enter the code into the address bar on the target page, but I want to pass this argument through a link.. ie...
<a href="/nextpage.php?javascript:alert(document.getElementsByClassName('uiTextareaNoResize uiTextareaAutogrow _1rv DOMControl_placeholder')[0].value='blabla');"
Just wondered if anything like this is possible at all?

You can send the arguments via the url like you would for GET requests. Then have the receiving page parse location.search.
For instance, you can send it like this:
http://example.com/?arg1=foo&arg2=bar
And the receiving page have a script like this:
var queryString = location.search; //?arg1=foo&arg2=bar
You'll have to parse it manually though, removing the ?, split by & then each by =

This is called XSS or Cross-Site-Scripting, and as many comments have already pointed out, it is a security issue. This is why most major browsers do NOT allow it.
However, I believe that some browsers do allow it, for example Opera - although I can't recall exactly which version.
If you are looking to make your own "browser", I would recommend using C# .Net WebBrowser, then use the runtime package XULRunner (https://developer.mozilla.org/en-US/docs/Mozilla/Projects/XULRunner).
Despite all this, I would not recommend doing anything that may be against laws of your current location, or doing anything to displease the site owner.

Anchor element's pathname returns undefined in Rhino with env.js

I have run into an issue that I believe is rooted in the implementation of anchor tags in Rhino. Although I am utilizing env.js, I suspect perhaps I am not configuring something correctly.
In particular, my issue occurs while I am attempting to write unit tests against code written for an angularjs application. When I include angular.js (versions 1.2.1 to present), I get the following error:
TypeError: Cannot call method "charAt" of undefined
I am convinced the error is the result of this call to urlParsingNode.pathname since a console.log call reveals that the pathname object is undefined.
I traced the instantiation of the urlParsingNode to this line where we see that it is the result of a call to document.createElement("a"); Further down, we see that they set the href attribute in this line in hopes that the created anchor tag will utilize the browser to correctly parse the URL.
I have to believe I'm not the first to attempt JS unit testing for angular via Rhino, but thus far I've not successfully Googled myself to a solution. Any tips will be greatly appreciated.

Found it and fixed it. The pathname getter/setter simply was undefined for HTMLAnchorElement in env.js.
I submitted a pull request, but unfortunately the project looks all but abandoned. I also couldn't figure out how to build it out to a single file. It appears perhaps someone has taken it upon themselves to break it apart into require.js modules. Not a battle worth fighting for my use case.
So for anyone else who hits this issue, I have the code you need below. It belongs in the HTMLAnchorElement.prototype. In my copy of env.js 1.2, this prototype begins on line 8075. I added the following at line 8118.
get pathname() {
var uri = Envjs.urlsplit(this.href);
return uri.path;
},
set pathname(val) {
var uri = Envjs.urlsplit(this.href);
uri.path = val
this.href(uri.urlunsplit(uri));
},
FYI, my particular issue is resolved with this pull request.

Weird 'ChildNodes of undefined' error in IE8 with an AngularJS application

TypeError: Unable to get value of the property 'childNodes': object is null or undefinedundefined
After making a long list of modifications to my application in order to support IE8, including:
running all of the views in their compiled form through W3C validator, setting up xdomain.js proxy to support CORS API calls, making some general restructures, etc.
I was very disappointed to find out that IE8 still throws this weird error at me, while IE9 works perfectly fine.
Making changes to the Angular-seo package to prevent it from running when the client is an IE browser.
Any ideas on what can it be?.

Make sure that all your tags are closed properly. I just spent hours trying to figure out what the problem was, until I noticed this in my code:
<span>some text<span>
I finally realized I didn't close the <span> tag properly. After that everything just worked.

Without the code you are running it is a bit difficult. However there is a command to use for debugging. First you need to identify which variable might not contain an object [i.e.
"object is null or undefined"].
For example, parent, then you can use
//next look to see if parent is something
if('undefined'==(typeof parent)) alert("variable empty:parent");
Once you find something that is empty that you are expecting to be an object then you can go trace back from there. Also use a browser debugged tool, to identify the line number of the error.
Often if using the child nodes, you may not have the right level or you need to access as an array i.e. you need something like.
parent.childNodes[0].childNodes[0].value
In IE you are also dealing with unsupported functions. So getElementById will work but some other similar ones do not. Again typeof can be useful.
//next ensure function supported
if( 'undefined'==(typeof document.getElementsByClassName) ){
alert("Not Supported"); // notice ^ no () required here
//...add code to handle differently when not supported
}
This may reveal if you can use a function

IE8 is so old and non-standards compliant it doesn't support childNodes[]. http://quirksmode.org/dom/core/#t70

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

Setting breakpoints dynamically at runtime in Javascript

Both firebug and the built in console in webkit browsers make it possible to set breakpoints in running Javascript code, so you can debug it as you would with any other language.
What I'm wondering is if there is any way that I can instruct firebug or webkit that I'd like to set a breakpoint on line X in file Y at runtime, and to be able to examine variables in the specific scope that I have paused in.
I need something that can work in both Chrome (or any other webkit browser) and Firefox. For the latter Firebug is an acceptable dependency. Supporting IE is not a requirement.
I've been building an in-browser IDE ( quick video for the interested: http://www.youtube.com/watch?v=c5lGwqi8L_g ) and want to give it a bit more meat.
One thing I did try was just adding debugger; as an extra line where users set them, but this isn't really an ideal solution.

I'd say you can definitely do this for webkit browsers using the remote debugging protocol. This is based on a websocket connection and a json message protocol that goes back and forth.
You can read the announcement and the whole protocol schema.
Chrome also offers more information about this inside its remote developer-tools docs.
For the debugger domain, for instance, you can see how you can use Debugger.setBreakpoint, Debugger.setBreakpointByUrl and Debugger.setBreakpointsActive to work with breakpoints.
On the other hand, Mozilla also seems to be working on this as you can see in https://developer.mozilla.org/en-US/docs/Tools/Debugger-API and https://wiki.mozilla.org/Remote_Debugging_Protocol though I don't know the completion status of it.
In this case, you can work with breakpoints using the Debugger.Script APIs setBreakPoint, getBreakPoint, getBreakpoints, clearBreakpoints and clearAllBreakpoints
I hope this helps you move forward.

There isn't such a thing, at least not using the public, scriptable side of JavaScript. It would be possible if you have a privileged browser extension that could do that for you. For example, Firebug has a debug method which you can call from its command line, but not from scripts inside a page.
So, you have two solutions:
Implement your own JavaScript interpreter, which you can control as you wish. Might be a bit too ambitious, though...
Rely on a browser extension that can set breakpoints anywhere in the code, expose some API to public code, and interact with it from your JavaScript. But that means that users will have to install some extra piece of software before they can use your "Web IDE".

Use _defineSetter__ to watch variables, and combine it with a call to debugger when an assignment happens.
__defineSetter__("name", function() { debugger; });
or defineProperty:
function setter () { debugger; }
Object.defineProperty(Math, 'name', { set: setter });
References
MDN: Object.defineProperty
A List Apart: Advanced Debugging With JavaScript
JavaScript Getters and Setters