I have been trying to turn a bookmarklet into a small development environment that I can use for testing some javascript and sending commands easily on the fly and updating the code on my server quickly to see the result. This has half way worked using method's I have found in this site and google however it doesn't seem to work very well and sometimes randomly doesn't work. The end goal is to have a bookmarklet that I can click on from any page and it loads a javascript file I have saved on my server. I have created the following two bookmarklets to try and get this working:
Failed Method 1:
javascript:
var s = document.createElement('script');
s.type='text/javascript';
document.body.appendChild(s);
s.src='//smewth.com/test.js';
void(0);
Method 1 in one line bookmarklet form: javascript: var s = document.createElement('script'); s.type='text/javascript'; document.body.appendChild(s); s.src='//smewth.com/test.js'; void(0);
Failed Method 2:
javascript:(
function(){
var imported = document.createElement('script');
imported.type='text/javascript';
imported.src = 'https://smewth.com/test.js';
document.head.appendChild(imported);
})();
Method 2 in one line bookmarklet form: javascript:( function(){ var imported = document.createElement('script'); imported.type='text/javascript'; imported.src = 'https://smewth.com/test.js'; document.head.appendChild(imported); })();
I got method 1 by decomposing the kickass bookmarklet from (http://kickassapp.com/). The actual one I got from their site works fine on my browser no problems. I even did a direct substitution from the URL they were using to load with my URL. The second method I found while searching on this site and this actually worked for a small while and stopped working for some unknown reason (maybe different browsers). I tried appending this script object to the head and the body on each of them with no improved results.
I created the test.js script just for this post and it contains a simple alert box statement:
$$ [/]# cat test.js
alert("hi");
$$ [/]#
NOTE: When I do this with the code embedded within the the bookmarklet itself without appending it to a head/body object then it works fine such as this:
javascript:%20alert("hi");
I did notice that with both of these methods, the code is actually getting injected into the page however I am not seeing the code is ever executed when I click the bookmark. Does anyone know which method is the best or something similar to do this so I can have javascript load through a page which I update on a remote server (reliably)? Maybe I need to attach the to a different object?
Thank you for your help.
-Jeff
UPDATE: I am showing this works while this site is loaded but it doesn't work when your at a site like google.com. Not sure what the difference is or how to accomodate this, google.com has a head and a body object too. I am showing this works in some sites and in some it doesn't.
I figured this out. There were two things occurring which accounts for the intermittent symptom of this issue. The first issue was that the site which was hosting the code was on a self-signed certificate. I began to notice the issue was occurring only when trying to run this from within secure sites. Then in Chrome I saw a error show up in the console. It would be nice if Firefox gave me a error on the console or something as this was the root of the issue. The second thing I had to do was disable OCSP in Firefox as I used a free certificate for testing purposes.
I also had to use method 1 as described above. Firefox and Chrome both did not like the anonymous function call for some reason. From now on I will refer to Chrome to look for errors in the console as Firefox has proven itself not very useful for this.
We have an unusual problem with javascript running on IE 11. I tried it on one of our servers running IE8 and the same problem occurs. However, it runs fine on Chrome and Mozilla.
Here's the code in question:
SetGuideFatningCookie(fid); //set a cookie according to user choice
var validFatningCombo = ValidFatningCheck(); //ask server if user choice is valid using XMLHttpRequest GET request
if(validFatningCombo)
window.location.href = GetGuideTilbehoerURL(); //if valid redirect user to next page
else
popAutoSizeFancy("#GLfancy"); //if not show a fancybox with error text
The user chooses one of 7 choices. Then they click a button that runs the above code. The code sets a cookie containing the user's choice and asks the server if the choice is valid. If valid - we redirect the user and if not, we open a fancybox that contains some error text and two buttons - "Try again"(closes box and they can try again) and "Send us a message"(redirects user to our "ask us a question" page).
The code runs fine the first time the user goes to this process.
However, if they have chosen an invalid choice, they close the fancybox and try to choose another choice and continue -> then the fancy box appears ALWAYS, regardless of what the user chooses.
If they choose a valid choice and continue, get redirected to next page, then come back to this page and choose an invalid choice and press continue -> then they can continue to the next page without fancybox ever coming up.
However, if IE's developer tools are opened, the code runs correct every single time.
I have found many threads describing this is a problem with console.log. I have removed every single reference to console.log from all our .js files. It could be one of the external libraries that we are using, like jquery, modernizr, fancybox and menucool's tooltip library.
Therefore I tried including a console fallback function for IE, like this thread suggests:
Why does JavaScript only work after opening developer tools in IE once?
I am currently trying with this one, and I have tried every single other fallback console replacement from the thred I link to.
if (!window.console) window.console = {};
if (!window.console.log) window.console.log = function () { };
I tried including it:
Somewhere in our .js files
script element in head after loading all our .js files and all external libraries
script element in head before loading all our .js files and all external libraries
Inside $(document).ready(function() {}); , in a script element in head after loading all other js
So far, none of the fallback pieces of code I have tried in any of these 4 locations have solved the problem. It always behaves the same way in IE. I couldn't find another explanation than the "console" one for this problem so far, so if anyone got any insight on it, it would be greatly appreciated.
EDIT: I will include some more info:
The very act of opening Developer Tools removes the unwanted behaviour. No errors are ever shown in console.
I checked the server side to see if the server is getting the call from ValidFatningCheck(); It turns out that the call is made only the first time (or if Developer tools is open - every time) which is rather mysterious since the redirect/fancybox line comes after the server call and it doesn't fail to run, even if it runs wrong.
function ValidFatningCheck(){
var requestUrl = '/Tools.ashx?command=validscreen';
var req = new XMLHttpRequest();
req.open('GET', requestUrl, false);
req.send(null);
var res = "";
if (req.readyState==4)
res = req.responseText;
if(res == "true")
return true;
return false;
}
UPDATE : Problem solved by adding a timestamp to my XMLHttpRequest as multiple replies suggested. I didn't realize XMLHttpRequest uses AJAX so I overlooked it as a probable cause to the problem.
(I put in comments but will make this an answer now as it appears to have solved the problem) get requests are cached by IE but when the developer console is open it does not perform this cache.
three ways to fix:
add a timestamp to the request to trick the browser into thinking it is making a new request each time
var requestUrl = '/Tools.ashx?command=validscreen&time='+new Date().getTime();
set the response header to no-cache
make a POST request as these are not cached
(as pointed out by #juanmendes not ideal you are not editing a resource)
In the Net pane of developer tools I can see all the various scripts that are called on a webpage. I can do Ctl+F on the html source to find the script, or link to the script (like with the src attribute).
Sometimes however, scripts call scripts which are called by other scripts, so I can't see the actual reference to the script on the page. Is there anyway I can see exactly what called a particular script. Like a way in the net panel (eg on mainsite.com) I could see b.thomas.com was called by the call a.thomas.com. Then I could see that on the page, the chain started with <script src="a.thomas.com" type="text/javascript"></script>. The header I see in dev tools always simply says mainsite.com.
See my answer at https://stackoverflow.com/a/19565853/432681.
Firebug is currently not able to display the origin of a request directly because of missing APIs in Firefox, though you can use the Referer header of each request as an indication.
I'm using an affiliate program which in this case means once a customer press the "order" button, he/she will get directed to the sellers website. The seller then registers that the customer came from OUR button, which is done by using a tracker that he registrates. This tracker gets executed on the "Order" button click, using the following code:
<script type="text/javascript">
$(function() {
function injectFile(filePath) {
var newScript = document.createElement('script');
newScript.type = 'text/javascript';
newScript.src = filePath;
document.getElementsByTagName('body')[0].appendChild(newScript);
}
$('#custom_form').on('success.form', function() {
injectFile('https://example.com/&ti=' + Math.round((new Date().getTime() * Math.random())) + '&charset=ISO-8859-1');
});
});
</script>
I removed the actual URL and most of the parameters. ti represents an order ID that is needed for the reg to work, but it doesn't have to be valid. The above math generates a random number and inserts it.
By tracking the HTTP headers, I can confirm that this works in both Firefox and IE, since it requests the URL properly. In Chrome however, no request is registered and the seller won't see the customer coming from my end.
Sometimes the Chrome console displays this: "Resource interpreted as Script but transferred with MIME type text/html." However, this is just a warning and since it defines it as a script anyway it shouldn't affect the execution? Weird thing here is I don't get this error each time.
I have tried just about everything and I can't see why Chrome wouldn't be compatible with such a basic functionality. Is there a possible workaround or an actual fix to my issue?
Thanks in advance,
Fredrik
This is a bad configuration of the Apache / Nginx configuration of the remote server.
The mime-type of the file is not "text/javascript".
But no effect on your code ;)
Try running your code in an incognito window or a fresh install of Chrome - some extensions block asynchronous script loading from advertising or tracking sites in a way that is hard to detect.
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.