Getting data from the browser's console using javascript - javascript

I don't know if this has been asked before, but what i'd like to be able to do is get data from the error console within the browser itself(if it supports it) this would be for when a user sends off a bug report it'd pull up any errors related to pages at my website for things such as typos in code and other things that somehow managed to slip by. Also, in that regard is there a way to pass the errors from the console to a useable format? If this isn't possible, then i could just tell them to copy and paste what came up from the site itself.
I thought of this right now as i was thinking about how to make the bug reporting system run better since the entire thing is basically ran within the browser and for the backend I can easily just look at error logs but for the frontend ie javascript bits of things it's not goign to be as easy.
So to finish wrap all of this up in one little statement, is there an easy way to get the data from the error console and be able to send it along via javascript ie to a form, or something similar.

You can use the onerror event in JS to get the details of the error. Hoptoad do this for example and log the errors to their console, Their code re-uses lots of nice JS scripts including a printStackTrace function that is great.....
You can see how they do it here:
http://hoptoadapp.com/javascripts/notifier.js

Related

Define custom function in Firebug

I am a chronic user of Firebug, and I frequently need to log various stuff so that I can see what I am doing. The console.log function is a lot to type. Even if I assign it to a single letter variable like q = console.log, I have to do it every time I fire up Firebug. Is there any way to do it such that q always refer to console.log (unless, of course, I override it in my session)?
To answer your question, the functionality doesn't currently exist, however I have found the firebug developers to be very responsive in the past. Why don't you put in a feature request on their forum, or better yet, code it up yourself, and ask them to add it?
Depending on your IDE, simply setup a code snippet (I use Flash Develop, so Tools -> Code Snippets).
I believe this to be a better way than setting up redirect scripts and what not, because it stops the Firebug namespace from being polluted, and makes it easier/more consistent to debug if your debugging breaks down.
The screenshot shows me using Flash Develop, hitting Ctrl+B, then hit enter. The pipe (|) in the snippet indicates where the cursor will be placed to start typing after inserting the snippet.

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

Where does rails log errors in javascript?

I'm fairly new to Ruby on Rails so sorry if the answer is obvious, I couldn't find anything via search. Right now I have my view rendering _box.js.erb which simply draws a box. Inside _box.js.erb, which works correctly under normal circumstances, I introduce a simple syntax error like an unmatched parenthesis. When I load the webpage, my box doesn't show up. I look in logs/development.logs and it has no mention of my javascript syntax error. Is this error being caught somewhere? If so, how can I display it?
The error occurs on the client, not the server, so ROR cannot log it.
If you're using Firefox, install Firebug. Other browsers have JavaScript consoles, usually opened by pressing F-12 or looking on the "developer" options on the application menus.
You could also create a controller to accept javascript errors, so when there's a client side error you can just send it to a javascript error collection endpoint which in turn could take the contents of the error and add it to the Rails log or whatever log.
This old gem does that. I realize this questions is 8 years old.

Ajax problem using MooTools/jQuery - p.onStatusChange is not a function

I get the following error in firebug in Firefox 3 with both MooTools and jQuery:
"p.onStatusChange is not a function".
I've noticed this error frequently in firebug since one of the latest updates of FF3. However, it has started appearing with code that hasn't been changed in some time and that was not reporting errors previously. The errors happens when ajax results are returned. It shows up in different applications that use separate javascript libraries, MooTools and jQuery.
Does anyone have any idea why these errors are appearing? My intuition tells me that it is something in Firefox that changed, but I can't find any information online currently. The ajax calls still work fine, but I am wary of just going with my intuition and leaving script errors in my code.
Thanks,
Jason
I get it in tabBrowser instead:
chrome://browser/content/tabbrowser.xml
(4) errors occur:
p.onStatusChange
p.onProgressChange
p.onStateChange
p.onSecurityChange
What I found was that the add-on "PDF Download" was causing these errors. The best way for me to check was to go to a page that produced the errors, turn off all the add-ons, and turn them on one-by-one (starting with Firebug). Instead of going one-by-one, I actually turned them on in lots of 3 to help identify the problem sooner.
Here is the reference for the function NsIDownloadProgressListener. It looks like it has been deprecated.

inspect javascript calls for gmail's buttons

i'm working on a greasemonkey script for gmail in which it'd be very useful to know what function call is made when the "send" button is clicked. (i was unable to find this using firebug, but am relatively new to javascript debugging.) it seems that one should be able to detect this, i just don't know what tool(s) to use.
thanks very much for any help.
p.s. ultimately the goal here is to be able to extract a unique message i.d. for outgoing gmail messages, which i figured would be present in this javascript call -- so if there's an alternate way to do this, that would work just as well.
Gmail's Javascript code is obfuscated to avoid this type of inspection (and also to reduce code size). It is very unlikely you'll be able to make heads or tails of it even if you manage to get Firebug to breakpoint in the code properly.
I don't think that the message id would be in the message created (in fact all the headers would be absent). My guess is that they are entered on the server side by Google before dispatching the message.
All objects in JavaScript has got a toString() method. If you can find the button then you can find it's associated events. You can then toString() those events in the FireBug console--but as levik wrote; all of the code if obfuscated, so you might just end up toString()'ing gibberish.
Here's a little pseudo-code to get you started:
document.getElementById("...").onclick.toString()
Update
It seems like it's not possible to access events added with attachEvent() and addEventListener() if you have no control over the code you want to debug.
As a sidenote, one would assume that the unique id gets assigned in the server, not in the javascript...

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