I'd like to do this in Chrome Developer Tools, but I'd take anything at this point.
The question
If I know I am looking for a specific object, how can I search the entire JS hierarchy to find it?
The situation
In know from my time on irc://irc.freenode.net/bash that when people reduce their question to what they think they should do, they waste a lot of time.
I use Confluence Cloud and their WYSIWYG is terrible. Because it is TinyMCE, I can get a lot done by editing the DOM in the Chrome Developer Tools. I ought to be able to hack the JS object and get even more through. But, the first step is the find the TinyMCE.settings object.
If you've got a reference to the object's constructor, the queryObjects() API might be able to help you locate the object. You might need to set a breakpoint and pause the code at a point where you know that the object still exists in the heap.
Check what version of Chrome you're using at chrome://version. queryObjects() was introduced in Chrome 62, which should be hitting Stable right about now but you might not have it quite yet.
Related
I have a complex Angular application which uses pure cesium.
The problem is that at startup I have a lot of warnings like this:
Violation ‘requestAnimationFrame’ handler took 742ms.
Violation ‘load’ handler took 80ms.
I tried to use setTimeout for the creation of the Viewer object, but it just makes the warnings occur later.
What do you recommend me to do?
Thanks in advance
I have such problem, I find this answer on https://forum.playcanvas.com/t/solved-chrome-warnings/12558/2
from #Albertos,
I think this will help you!!!
“Chrome violations” don’t represent errors in either Chrome or your own web app. They are instead warnings to help you improve your app. In this case, Long running JavaScript and took 83ms of runtime are alerting you there’s probably an opportunity to speed up your script.
(“Violation” is not the best terminology; it’s used here to imply the script “violates” a pre-defined guideline, but “warning” or similar would be clearer. These messages first appeared in Chrome in early 2017 and should ideally have a “More info” prompt to elaborate on the meaning and give suggested actions to the developer. Hopefully those will be added in the future.)
Are there any plugins that would do this? Let's say you highlight a code block, when you press undo, it undoes the last change with in that code block?
I've done a lot of digging into Sublime's internals, and I don't think this is possible. Commands (processes executed when you select a menu item or hit a key combination) are implemented in one of two ways: either in Python, making use of the API, or internally in C++ and compiled directly into the executable or a library. If a command is implemented in pure Python, such as delete_word (source in Packages/Default/delete_word.py), you can edit the source if necessary or take portions to use in your own code. However, if a command is implemented internally, there's not much you can do to modify it, unless it has options that are documented somewhere. You basically have to use it as-is.
Which brings us to the undo/redo commands, and the edit history. As far as I can tell (since Sublime is not open source - yet), this entire functionality is completely implemented internally, with only the command names exposed. I have been completely unable to find any way of viewing or accessing the actual changes made to the undo/redo stack. The command_history() method of the sublime.View class accesses the commands in the undo/redo stack, but not the actual changes they made.
So, all of this is to say that one could not likely make a plugin that could access the change history of an arbitrary selection in Sublime. One of the major issues (aside from the fact that the change history of the view is not accessible) is that the text you select now might not correspond to anything at a certain point in the history - it might not exist, or could have been altered so fundamentally that it would be essentially impossible to identify which changes should be associated with the selection, and which not. I have never heard of a similar feature in any other editor, most likely for that exact reason.
I'm processing a variety of RSS feeds, which contain summaries, as well as the target page URL content, and trying to use a uniform transformation method.
XSLT was the first thing that occurred to me to try, as it would accomplish what I want, in a standard way, without a lot of fuss aside from adding new XSLT stylesheets to accommodate uniquely formatted sites and feed content.
Problem: XSLT libraries are considered "private" in iOS, and even linking statically against your own copy will get you rejected by the Apple Store analysis tools.
I've looked into the possibility if injecting the stylesheet and data into a UIWebView that wasn't displayed, but this seems like a really roundabout and hackish way to get at the system's underlying XSLT processor in an "approved" fashion.
What alternative techniques/libraries exist which would let me do this in a standard fashion, ie: without rolling my own.
I'm not sure I fully understand your requirements, but one possbility would be to use libxml (which is allowed in iOS) to parse the XML and if necessary manipulate the DOM. If you really need to do XML transformations this is going to be more effort than XSLT, but if you just need to extract data from the XML, that can be done fairly easily with xpath queries.
That said, I have read several people claiming they got XSLT working on iOS and had their apps approved in the app store. In particular, I've seen this stackoverflow answer claimed as a working solution by multiple people. And if that fails, another answer suggested building the libxslt library yourself with renamed symbols to bypass the app store checks. I would only suggest that as a last resort though.
You'll probably want to look into Hpple for something powerful but light weight / native. See the tutorial on getting started here: http://www.raywenderlich.com/14172/how-to-parse-html-on-ios. Good luck!
I'm going to also recommend TFHpple but I'm also going to elaborate on the solution. I've explored an app that navigates a 3rd party (well, I'm the 3rd party, they're the source but that's semantics) website/data source but there are some pitfalls. The biggest pitfall is obvious: if the data source DOM changes you need to change your app and re-release. A creative way around this would be to publish/expose a global copy of the DOM on a public server that way the end user doesn't have to update their app any time the data source changes (as long as the change isn't radical).
For instance, if your expected DOM search in TFHpple is #"//figure[#class='figure']/a" and then a week from now your data source's resource you're looking for is altered to #"//figure1[#class='figure1']/a" you just opened yourself to an App Store release... UNLESS... you publish the expected DOM searches on a web server you control in a data dictionary that your app can consume and serve out to the various DOM search elements within your app. The only problem I foresee here is that if the data source adds or removes a data element you want to consume you either have to release a build or handle the removal ahead of time (respectively).
Lastly if the data source DOM isn't well formed or consistent you may be beating your head against a wall more times than not.
In the company I am I was asked to write an autoupdate function a la chrome. I.e. It should check periodically whether a new version is available, download the new version and apply it silently the next time the application starts.
I already have something up and running but it is more like a dirty hack than something I feel happy about it. So, I would like to know how to design and implement such a solution. My horrible hack works as this:
Have a mechanism to check whether a new version exists (a database query or a web service)
Download a full zip with the whole new version.
Check file signature. If everything went alright, set a registry value: must update to true.
When the application restarts, if the must update value is true, launch an update program and exist.
The update deletes the contents of the application folder, unzips the update and replaces the old contents, launches the application and exits.
Now, I would like to change it, so it works cleaner. I am planning to send the update as a bsdiff file. It gets downloaded. But the question is, what happens next?
When do apply the update?
Who is in charge of applying the patch? is it the program itself or is it a third program, as I did, which is in charge of applying the patch and relaunch the application?
If your going down the C++ route you can go to chromium and download the Chrome source code and dig around to see how the update is done, this might give you a better idea on how to approach it. Here's an article that might help.
If your familiar with .NET the recently release nuget also has an auto update feature that might be useful to look at, you can get the source code from here. David Ebbo has a blog about how its done here.
I'm not up to date on Delphi but you might be able to use either of the above options.
The workflow you proposed is more or less like it should work, but there's no need to re-invent the wheel - there are plenty libraries out there that will do this for you. Using a 3rd party library has the benefit of keeping your code cleaner while making sure the dirty process of auto-update is contained and working flawlessly.
Trust me, I know. I'm the author of NAppUpdate, an app update framework for .NET (which you might want to try out or learn from).
So, after giving it a lot of though, this is what I came with (for active directory I will refer to the directory where the main program lies, active program is the main program and update program is the one that replaces the active program and its resource files):
The active program checks if there is a new version every certain amount of time. If so, download it
Prepare new version in a separate folder (this can be done by copying the contents of the directory with the program to a subdirectory and applying a binary patch, or simply unziping the new version).
Set a flag that indicates that a new version is ready.
When a program is exiting (and one has to control for different interrupts here):
The active program checks the new version ready flag. Launch the update program and exit.
The update program checks if it can write in the active directory. If so, replaces the contents with the prepared version.
The update program has to recheck links and update them accordingly.
So guys, if you have a better workflow, please tell me.
You could literally use the Google Chrome update workflow by using the Google Chrome updater:
http://code.google.com/p/omaha/
They open sourced it Feb 2009.
Imagine i have a function with a bug in it:
Pseudo-code:
void Foo(LPVOID o)
{
//implementation details omitted
}
The problem is the user passed null:
Object bar = null;
...
Foo(bar);
Then the function might crash due to a access violation; but it could also happen to work fine. The bug is that the function should have been checking for the invalid case of passing null, but it just never did. It was never issue because developers were trusted to know what they're doing.
If i now change the function to:
Pseudo-code:
void Foo(LPVOID o)
{
if (o == null) throw new EArgumentNullException("o");
//implementation details omitted
}
then people who were happily using the function, and happened to but not get an access violation, now suddenly will begin seeing an EArgumentNullException.
Do i continue to let people using the function improperly, and create a new version of the function? Or do i fix the function to include what it should have originally had?
So now the moral dillema. Do you ever add new sanity checks, safety checks, assertions to exising code? Or do you call the old function abandoned, and have a new one?
Consider a bug so common that Microsoft had to fix it for developers:
MessageBox(GetDesktopWindow, ...);
You never, ever, ever want to make a window model against the desktop. You'll lock up the system. Do you continue to let developers lock up the user's computer? Or do you change the function to:
MessageBox(HWND hWndParent, ...)
{
if (hWndParent == GetDesktopWindow)
throw new Exception("hWndParent cannot be the desktop window. Use NULL instead.");
...
}
In reality Microsoft changed the Window Manager to auto-fix the bad parameter:
MessageBox(HWND hWndParent, ...)
{
if (hWndParent == GetDesktopWindow)
hWndParent = 0;
...
}
In my made up example there is no way to patch the function - if i wasn't given an object, i can't do what i need to do on it.
Do you risk breaking existing code by adding parameter validation? Do you let existing code continue to be wrong, getting incorrect results?
The problem is that not only are you fixing a bug, but you are changing the semantic signature of the method by introducing an error case.
From a software engineering perspective I would advocate that you try to specify methods as best as possible (for instance using pre and post-conditions) but once the method is out there, specification changes are a no-go (or at least you would have to check all occurrences of the method) and a new method would be better.
I'd keep the old function and simply let it create a warning that notifies you of every (possibly) wrong use and then i'd just kick the developer who used it wrong until he uses it properly.
You cannot catch everything. What if someone wrote "MakeLocation("Ian Boyd", "is stupid");"? Would you create a new function or change the function to catch that? No, you would fire the developer (or at least punish him).
Of course this requires that you document what your function requires as input.
This is where having automated tests [Unit testing, Intergration Testing, automated functional testing] are great, they give you the power to change existing code with confidance.
When making changes like this I would suggest finding all usages and ensuring they are behaving how you belive they should.
I myself would make bug fixes to existing function rather them duplicating them 99% of the time. If it changes behavior alot and there are a lot of calls to this function you need to be very sure of your change.
So go ahead make your change, run your unit tests, then your automated functional tests. Fix any errors and your golden!
If your code has a bug in it you should do what you normally do when any bug is reported. One part of that is assessing the impacts of fixing and of not fixing it. Sometimes the right thing to do with a bug is to not fix it because the behaviour it exposes has become accepted. Sometimes the cost of fixing it, or the iconvenience of releasing a fix outside the normal release cycle, stops you releasing a fixed bug for a while. This isn't a moral dilemma, it's an economic question of costs and benefits. If you are disturbed at the thought of having known bugs in your published code, publish a known-bugs list.
One option none of the other respondents seems to have suggested is to wrap the buggy function in another function which imposes the new behaviour that you require. In the world where functions can run to many lines it is sometimes less likely to introduce new bugs to preserve a 99%-correct piece of code and address the change without modifying existing code. Of course, this is not always possible
Two choices:
Give the error checking version a new name and deprecate the old version (one version later have it start issuing warnings (compile time if possible, run time if necessary), two versions later remove it).
[not always possible] Place the newly introduced error check in such a way that it only triggers if the unmodified version would crash or produce undefined behavior. (So that users who were taking care in their code don't get any unpleasant surprises.)
It entirely depends on you, your codebase, and your users.
If you are Microsoft and you have a bug in your API that is used by millions of devs around the world, then you will probably want to just create a new function and update the docs on the old one. If you can, you would also want to update the compiler to give warnings as well. (Though even then you may be able to change the existing system; remember when MS switched VC to the C++ standard and you had to update all of your #include iostreams and add using stds to get simple, existing console apps working again?)
It basically depends on what the function is. If it is something basic that will have massive ripple effects, then it could break a lot of code. If it is just an ancillary function, then you may as well fix it. Of course if you are Microsoft and your other code depends on a bug in one of your functions, then you probably should fix it since that is just plain embarrassing to keep. If other devs rely on the bug (that you created), then you may have an obligation to the users to not break their code that you caused to be buggy.
If you are a small company or independent developer, then sure, go ahead and fix the function. If you only need to update yourself or a few people on the new usage then fixing it is the best solution, especially since it is not even a big deal because all it really requires is an added note to the docs for the function. eg do not pass NULL or an exception is thrown if hWnd is the desktop, etc.
Another option as a sort of compromise would be to create a wrapper function. You could create a small, inline function that checks the args and then calls the existing function. That way you don’t really have to do much in the short term and eventually when people have moved to the new one, you can deprecate or even remove the old one, moving the code to the new once between the checks.
In most scenarios, it is better to fix a buggy function, particularly if you are merely adding argument checks as opposed to completely changing the behavior of the function. It is not really a good idea to facilitate—read encourage—bad coding just because it would break some existing code (especially if the code is free!) Think about it: if someone is creating a new program, then they can do it right from the start instead of relying on a bug. If they are re-compiling an old program that depends on the bug, then they can just update the code. Again, it depends on how messy and convoluted the code is, how many people are affected, and whether or not they pay you, but it is quite common to have to update old code to for example initialize variables that hand’t been, or check for error codes, etc.
To sum up, in your specific example (given the information provided), you should just fix it.