How to catch cookie change/disappear in browser debug tools? - javascript

I have cookie disappearing in my webapp when it shouldn't (expring date is a year ahead).
Can I set breakpoint on cookie change or something?

In Firebug you had the chance to stop the JavaScript execution on cookie changes. The current DevTools don't provide such a feature yet.
For Firefox it is requested in https://bugzil.la/895893, and I've just requested to add it to Chrome's DevTools in https://bugs.chromium.org/p/chromium/issues/detail?id=1171347.
What you can do right now is to search through the code within the Debugger to find the places where the cookies are changed.
To do that, you have to
Switch to the Debugger panel
Press Ctrl+Shift+F to search within all files
Enter document.cookie and hit Enter
Set a breakpoint for each found statement setting this variable
As there's currently only this way to add, remove or change cookies in JavaScript, this should allow you to find the place where the cookie you're searching is removed.

Related

cookies not getting cleared in IE11 (cookie was set by writing to document.cookie via Javascript)

so I set some cookies manually via Javascript by writing to document.cookie and they are getting written fine.
I checked using
console.log(document.cookie)
My issue is that even if I manually cleared my history via
Internet options => Browsing History => Delete (making sure "Cookies
and other website data" is ticked)
Making sure "Delete browsing
history on exit" is ticked and "Cookies and other website data" is
also ticked
document.cookie still shows the cookie values I manually created.
Things I've tried:
Close the tab. Manually clear my history. And then reopen my page on a new tab
Close IE11 completely. Reopen the app. And then open my page on a new tab
Any ideas what I could be doing wrong?
Thanks
ps. While I can expire my cookie via Javascript. I cannot expect end users to do same. :)
I've seen this happen if the website is "a favorite" in IE11. Can you try the following?
Go to Internet options => Browsing History => Delete (untick "Preserve Favorites website data"). Click delete, and close IE11.
If your website is not a favorite, let me know.
If you've already cleared your cookies the normal way, have you tried unchecking (if set) the Preserver Favorites Website Data option under Delete Browsing History? Tools > Safety > Delete Browsing History OR Ctrl + Shift + Delete.
If the above doesn't work, try pressing F12 and then Ctrl + R to clear browser cache, confirm you want to delete the browser cache. There is also an option to clear cookies for that specific domain under the Cache tab in Developer Tools Window.
I had the same problem with IE11 working under Windows 8.1: somehow the delete Browser Cookie didn't take effect. I could verify it using Burp: the cookies were still sent to the website.
I tried the various options:
Internet options => Browsing History => Delete (untick "Preserve Favorites website data"). Click delete, and close IE11.
Manually typing 'Document.cookie = ""' into the Developer Console
Resetting IE to default configuration
The only thing that actually worked for me was clearing the Browser Cookies through the Developer Console, as mentioned by lloan. For IE11, it looks a bit different so if you are looking for it, here it is:
Open the Developer Tools using F12
Go to Network
Click on "Clear cookies for domain"
For screenshot, see here

Why do certain redirects cause Nexus Chrome browser to not run Javascript?

On the Chrome 18.0.1025469 browser for Nexus 7, 4.2.2. certain redirects seem to cause Javascript not to load.
For example the following page: http://jsfiddle.net/NTEQF/show/
has the javascript
alert(1)
On my nexus I see the the alert if I type in the following:
jsfiddle.net/NTEQF/show/
But if I type in (with a clear cache)
www.jsfiddle.net/NTEQF/show/
I can see the url redirect to jsfiddle.net/NTEQF/show/ but I see no alert.
Once I visit the page a few times, the alert starts to show up. To reproduce the no alert consistently, I can clear all the data through the devices setting panel: Apps > All > Chrome > Clear Data - Sometime clearing the cache through the privacy settings within Chrome does the trick too.
This means that there are situations where pages can load as if you have Javascript disabled when it is enabled. Any ideas as to what causes this or how to fix it aside from not using redirects? I have seen the issue both on redirects that remove and add www.
You must be consistent with redirects.
If you call www.whateverpage.com on one redirect and then just whateverpage.com on another, you are actually going to two different domains, so any cookies or session cookies might be set for one domain but not the other. This is true also if you have for example a page like mobile.whateverpage.com. These are all different domains, so you'll have to treat them accordingly.

cookie on a data uri page

My previous question about the same subject has given me 8 negative votes. I hope now to be clearer.
If you run
document.cookie ='ppkcookie1=testcookie;';alert(document.cookie);
on any web page the content of the cookie appears in the message box.
if you run the code above inside a very simple data-uri page (you could copy and paste the following string on the address bar in FF or Chrome, since IE does not support it)
data:text/html;charset=utf-8,<h1>hi people</h1><script>document.cookie='ppkcookie1=testcookie;';alert(document.cookie);</script>
the message box is empty
Does this mean that cookies cannot be used on data-uri pages or there is some errors in my piece of code?

"undefined" randomly appended in 1% of requested urls on my website since 12 june 2012

Since 12 june 2012 11:20 TU, I see very weirds errors in my varnish/apache logs.
Sometimes, when a user has requested one page, several seconds later I see a similar request but the all string after the last / in the url has been replaced by "undefined".
Example:
http://example.com/foo/bar triggers a http://example.com/foo/undefined request.
Of course theses "undefined" pages does not exist and my 404 page is returned instead (which is a custom page with a standard layout, not a classic apache 404)
This happens with any pages (from the homepage to the deepest)
with various browsers, (mostly Chrome 19, but also firefox 3.5 to 12, IE 8/9...) but only 1% of the trafic.
The headers sent by these request are classic headers (and there is no ajax headers).
For a given ip, this seems occur randomly: sometimes at the first page visited, sometimes on a random page during the visit, sometimes several pages during the visit...
Of course it looks like a javascript problem (I'm using jquery 1.7.2 hosted by google), but I've absolutely nothing changed in the js/html or the server configuration since several days and I never saw this kind of error before. And of course, there is no such links in the html.
I also noticed some interesting facts:
the undefined requests are never found as referer of another pages, but instead the "real" pages were used as referer for the following request of the same IP (the user has the ability to use the classic menu on the 404 page)
I did not see any trace of these pages in Google Analytics, so I assume no javascript has been executed (tracker exists on all pages including 404)
nobody has contacted us about this, even when I invoked the problem in the social networks of the website
most of the users continue the visit after that
All theses facts make me think the problem occurs silently in the browers, probably triggered by a buggy add-on, antivirus, a browser bar or a crappy manufacturer soft integrated in browsers updated yesterday (but I didn't find any add-on released yesterday for chrome, firefox and IE).
Is anyone here has noticed the same issue, or have a more complete explanation?
There is no simple straight answer.
You are going to have to debug this and it is probably JavaScript due to the 'undefined' word in the URL. However it doesn't have to be AJAX, it could be JavaScript creating any URL that is automatically resolved by the browser (e.g. JavaScript that sets the src attribute on an image tag, setting a css-image attribute, etc). I use Firefox with Firebug installed most of the time, so my directions will be with that in mind.
Firebug Initial Setup
Skip this if you already know how to use Firebug.
After the installs and restarting Firefox for Firebug, you are going to have to enable most of Firebug's 'panels'. To open Firebug there will be a little fire bug/insect looking thing in the top right corner of your browser or you can press F12. Click through the Firebug tabs 'Console', 'Script', 'Net' and enable them by opening them up and reading the panel's information. You might have to refresh the page to get them working properly.
Debugging User Interaction
Navigate to one of the pages that has the issue with Firebug open and the Net panel active. In the Net panel there will be a few options: 'Clear', 'Persist', 'All', 'Html', etc. Make sure ALL is selected. Don't do anything on the page and try not to mouse over anything on it. Look through the requests. The request for the invalid URL will be red and probably have a status of 404 Not Found (or similar).
See it on load? Skip to the next part.
Don't see it on initial load? Start using your page and continue here.
Start clicking on every feature, mouse over everything, etc. Keep your eyes on the Net panel and watch for a requests that fail. You might have to be creative, but continue using your application till you see your browser make an invalid request. If the page makes many requests, feel free to hit the 'Clear' button on the top left of the Net panel to clear it up a bit.
If you submit the page and see a failed request go out really quick but then lose it because the next page loads, enable persistence by clicking 'Persist' in the top left of the Net panel.
Once it does, and it should, consider what you did to make that happen. See if you can make it happen again. After you figure out what user interaction is making it happen, dive into that code and start looking for things that are making invalid requests.
You can use the Script tab to setup breakpoints in your JavaScript and step through them. Investigate event handlers done via $(elemment).bind/click/focus/etc or from old school event attributes like onclick=""/onfocus="" etc.
If the request is happening as soon as the page loads
This is going to be a little harder to peg down. You will need to go to the Script tab and start adding break points to every script that runs on load. You do this by clicking on the left side of the line of JavaScript.
Reload your page and your break points should stop the browser from loading the page. Press the 'Continue' button on the script panel. Go to your net panel and see if your request was made, continue till it is found. You can use this to narrow down where the request is being made from by slowly adding more and more break points and then stepping into and out of functions.
What you are looking for in your code
Something that is similar to the following:
var url = workingUrl + someObject['someProperty'];
var url = workingUrl + someObject.someProperty;
Keep in mind that someObject might be an object {}, an array [], or any of the internal browser types. The point is that a property will be accessed that doesn't exist.
I don't see any 404/red requests
Then whatever is causing it isn't being triggered by your tests. Try using more things. The point is you should be able to make the request happen somehow. You just don't know yet. It has to show up in the Net panel. The only time it won't is when you aren't doing whatever triggers it.
Conclusion
There is no super easy way to peg down what exactly is going on. However using the methods I outlined you should be at least be able to get close. It is probably something you aren't even considering.
Based on this post, I reverse-engineered the "Complitly" Chrome Plugin/malware, and found that this extension is injecting an "improved autocomplete" feature that was throwing "undefined" requests at every site that has a input text field with NAME or ID of "search", "q" and many others.
I found also that the enable.js file (one of complitly files) were checking a global variable called "suggestmeyes_loaded" to see if it's already loaded (like a Singleton). So, setting this variable to false disables the plugin.
To disable the malware and stop "undefined" requests, apply this to every page with a search field on your site:
<script type="text/javascript">
window.suggestmeyes_loaded = true;
</script>
This malware also redirects your users to a "searchcompletion.com" site, sometimes showing competitors ADS. So, it should be taken seriously.
You have correctly established that the undefined relates to a JavaScript problem and if your site users haven't complained about seeing error pages, you could check the following.
If JavaScript is used to set or change image locations, it sometimes happens that an undefined makes its way into the URI.
When that happens, the browser will happily try to load the image (no AJAX headers), but it will leave hints: it sets a particular Accept: header; instead of text/html, text/xml, ... it will use image/jpeg, image/png, ....
Once such a header is confirmed, you have narrowed down the problem to images only. Finding the root cause will possibly take some time though :)
Update
To help debugging you could override $.fn.attr() and invoke the debugger when something is being assigned to undefined. Something like this:
​(function($, undefined) {
var $attr = $.fn.attr;
$.fn.attr = function(attributeName, value) {
var v = attributeName === 'src' ? value : attributeName.src;
if (v === 'undefined') {
alert("Setting src to undefined");
}
return $attr(attributeName, value);
}
}(jQuery));
Some facts that have been established, especially in this thread: http://productforums.google.com/forum/#!msg/chrome/G1snYHaHSOc/p8RLCohxz2kJ
it happens on pages that have no javascript at all.
this proves that it is not an on-page programming error
the user is unaware of the issue and continues to browse quite happily.
it happens a few seconds after the person visits the page.
it doesn't happen to everybody.
happens on multiple browsers (Chrome, IE, Firefox, Mobile Safari, Opera)
happens on multiple operating systems (Linux, Android, NT)
happens on multiple web servers (IIS, Nginx, Apache)
I have one case of googlebot following the link and claiming the same referrer. They may just be trying to be clever and the browser communicated it to the mothership who then set out a bot to investigate.
I am fairly convinced by the proposal that it is caused by plugins. Complitly is one, but that doesn't support Opera. There many be others.
Though the mobile browsers weigh against the plugin theory.
Sysadmins have reported a major drop off by adding some javascript on the page to trick Complitly into thinking it is already initialized.
Here's my solution for nginx:
location ~ undefined/?$ {
return 204;
}
This returns "yeah okay, but no content for you".
If you are on website.com/some/page and you (somehow) navigate to website.com/some/page/undefined the browser will show the URL as changed but will not even do a page reload. The previous page will stay as it was in the window.
If for some reason this is something experienced by users then they will have a clean noop experience and it will not disturb whatever they were doing.
This sounds like a race condition where a variable is not getting properly initialized before getting used. Considering this is not an AJAX issue according to your comments, there will be a couple of ways of figuring this out, listed below.
Hookup a Javascript exception Logger: this will help you catch just about all random javascript exceptions in your log. Most of the time programmatic errors will bubble up here. Put it before any scripts. You will need to catch these on the server and print them to your logs for analysis later. This is your first line of defense. Here is an example:
window.onerror = function(m,f,l) {
var e = window.encodeURIComponent;
new Image().src = "/jslog?msg=" + e(m) + "&filename=" + e(f) + "&line=" + e(l) + "&url=" + e(window.location.href);
};
Search for window.location: for each of these instances you should add logging or check for undefined concats/appenders to your window.location. For example:
function myCode(loc) {
// window.location.href = loc; // old
typeof loc === 'undefined' && window.onerror(...); //new
window.location.href = loc; //new
}
or the slightly cleaner:
window.setLocation = function(url) {
/undefined/.test(url) ?
window.onerror(...) : window.location.href = url;
}
function myCode(loc) {
//window.location.href = loc; //old
window.setLocation(loc); //new
}
If you are interested in getting stacktraces at this stage take a look at: https://github.com/eriwen/javascript-stacktrace
Grab all unhandled undefined links: Besides window.location The only thing left are the DOM links themselves. The third step is to check all unhandeled DOM links for your invalid URL pattern (you can attach this right after jQuery finishes loading, earlier better):
$("body").on("click", "a[href$='undefined']", function() {
window.onerror('Bad link: ' + $(this).html()); //alert home base
});
Hope this is helpful. Happy debugging.
I'm wondering if this might be an adblocker issue. When I search through the logs by IP address it appears that every request by a particular user to /folder/page.html is followed by a request to /folder/undefined
I don't know if this helps, but my website is replacing one particular *.webp image file with undefined after it's loaded in multiple browsers. Is your site hosting webp images?
I had a similar problem (but with /null 404 errors in the console) that #andrew-martinez's answer helped me to resolve.
Turns out that I was using img tags with an empty src field:
<img src="" alt="My image" data-src="/images/my-image.jpg">
My idea was to prevent browser from loading the image at page load to manually load later by setting the src attribute from the data-src attribute with javascript (lazy loading). But when combined with iDangerous Swiper, that method caused the error.

How do you check cookies using Chrome?

I'm testing some cookies that I'm creating via JavaScript. Is there a way to check if the cookie was set in Chrome Developer Tools or something similar?
To check the current page's cookies using Chrome:
Option 1
Open Developer Tools (usually F12)
Click the "Application" tab (used to be "Resources")
Expand the "Cookies" list item
Click any list item.
You can view cookies in detail here, and clear them out (click any list item under cookies then click the cancel icon on the bottom left of the table).
Option 2
Use the javascript console, e.g. document.cookie. Less sophisticated (graphically), but you can work with the data using javascript. Note that the results will be restricted based on how websites are allowed to access local data from other sites (see MDN Same-origin policy).
Option 3
There is also chrome://settings/siteData (was previously settings/cookies). Just put the url into Chrome's address field.
In your console, type document.cookie. It will return the active cookies for that page.
Latest version of Chrome (v52) has moved this functionality to the "Application" tab. So updated steps are:
Open Developer Tools
Click the "Application" tab
Cookies are listed under the "Storage" list item on the left sidebar
Another method is to type the following:
chrome://settings/cookies
in the address bar.
Then use the left click to see more details (content, expiration date, etc.).
On the latest version of chrome Chrome v85 the url is:
chrome://settings/siteData
On chrome version 61:
chrome://settings/content/cookies
You can also use web developer tool which not only helps you to view cookies but also helps you to display.delete (session,domain,path) cookies individually.

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