IE8 is giving me the not-uncommon "A script on this page is causing your browser to run slowly" warning. Of course this only happens in IE and not in any other browser. I am using an Infragistics jQuery grid control that seems to be causing the warning.
On doing a little bit of research I learnt that while nearly every other browser displays the warning based on execution time (generally 5 or 10 secs), IE does it based on number of statements processed (5 million statements).
I want to be sure it is the grid control and not something else. Is there a way I can see the number of statements processed, maybe using something like Firebug or the IE developer tools?
IE8 has a profiler built in and it seems like no one knows it exists. IEBlog had a nice article explaining the profiler's features when IE8 was in BETA.
If you are using IE8 hit the F12 key and you will get a javascript debugger, step through the code and find the issue.
Firebug or chrome dev tools, you can see the timeline of execution.
Related
I have a very large javascript application, which contains mostly asm.js code (it's built upon urho3d c++ engine which is them compiled into asm.js).
It runs great on most browsers (chrome, firefox, safari, edge) but is extremely slow on IE11. The thing is, it is only slow until you open developer tools. With developer tools open, IE11 becomes ~10 times faster and is almost as fast as other browsers.
Here is a minimal example that reproduces the issue:
http://test.sebbia.com/urho3d/test.html
Open the page in any working browser, the time between "Run - start" message and "Run - finish" message should be around 1-2 seconds.
Open the page in IE11 without developer tools, time should be around 35-50 seconds.
Open developer tools and reload, time should be around 2-3 seconds.
Another important note is that if I start profiling session in developer tools, performance drops like if developer tools were closed. So I can actually profile the problem. But I've spent several hours profiling and I've tried inserting log messages in big functions but I haven't found no bottleneck. All functions take roughly the same time to execute and if I insert log message in a middle of a big functions, they'll usually break into 2 similar parts. So there is no single function that is responsible for slowdown, the code execution is just slow. Bit shifts, functions calls, arithmetic operations - it seems like they all just take way too much time compared to open developer tools.
I really need to make my app work on IE11 and the fact that it works with developer tools open drives me crazy. I'm trying to find a way to make IE think that tools are open even when they are not, or achieve good performance by any other means. So my questions is how can I achieve performance equal to IE11 with developer tools open without actually manually opening the tools?
This is a very broad question so I'd like to break it down into several smaller questions:
Is there a way to make IE11 think developer tools are open? Maybe there is something like x-ua-compatible meta tag I am missing?
What's causing the slowdown when developer tools are closed? I've heard that console.log function calls are slow without developer tools on IE8 and 9, maybe there is a similar thing on IE11? Maybe asm.js is not optimized? If I knew what's causing this I could at least try to rewrite code to avoid this.
Is there a way to open developer tools from javascript code? Maybe I could ask users to press a button on website to "make app faster". Asking them to press F12 or navigate settings seems too much.
When the debugger is enabled, asm.js compilation will be disabled and execution will fallback to be executed as normal JS - you can see the console.logs along these lines at the start of execution.
asm.js has been disabled as the script debugger is connected. Disconnect the debugger to enable asm.js. in Edge,
asm.js type error: Disabled by debugger in Firefox,
whilst Chrome will simply not open 01_HelloWorld.js in the debugger when you attempt to.
Disabling the debugger in IE (debugger tab, socket symbol; eighth from the left), and thus enabling asm.js will allow you to have dev tools open but see the slower execution. I have a horrible feeling that the slowdown when the debugger is closed is actually just IE11's speed issues with asm.js's optimisations.
There are a lot of references to IE11 being poorly optimised for asm.js. caniuse.com goes as far as listing IE11 as not supporting asm.js at all.
https://caniuse.com/#feat=asmjs
This appears to be backed up by Microsoft themselves:
https://developer.microsoft.com/en-us/microsoft-edge/platform/status/asmjs/
There would certainly appear to be some support for it, though clearly it has a number of speed issues as demonstrated in a number of benchmarks, for instance:
https://github.com/Kukunin/asm.js-benchmark/blob/master/README.md
Which shows IE11 around 10x slower than other browsers, or:
https://www.ghacks.net/2014/11/03/massive-benchmark-highlights-asm-js-performance-of-web-browsers/
Which is based on:
https://kripken.github.io/Massive/ - You can try it for yourself.
And many others. It may simply be that the IE11 implementation of asm.js is so poor that it is considerably slower with it, than without it.
EDIT: Added Microsoft platform status link.
There are two workaround for this issue:
to add setInterval(30000, () => {}) to your initialization function;
add MutationObserver=null to the beginning of the main html
You can also reference the discussion here:
https://github.com/OfficeDev/office-js/issues/521
This is just a guess but I had a similar problem in react-native then I found out about this:
When debugging remotely, your js bundle is using chrome's JSC and when
running on a device it's using the JSC provided by Apple on your phone.
Make sure that urho3d is not changing environment when developer tools are on/off.
I have more general question on how you usually approach on debugging page with tons of javascript (mostly third-party add-ons) and event watchers to discover the problematic line, which in my case causes the Chrome to crash or Firefox to freeze?
I have a landing page with many external dependencies: the usual suspects like jquery and bootstrap, but also many add-ons like sliders, re-size watchers. When I re-size there is a micro-freeze on Firefox and a crash on Chrome. This is from any block of code (some watchers most probably).
After page crashes I lose all of my dev tool data. Firebug doesn't have the timing control over scripts execution, and if I start with breakpoints I have to put dozens.
How you usually proceeding to identify the script that causes the problem and further more the block of code?
If I start with breakpoints I have to put dozens.
I used to have this problem a lot back with Internet Explorer 4/5. Those browsers made such poor use of memory that almost any significant error wold result in the browser crashing. And even before it did, the browser debugging tools were far, far worse than the Chrome ones. So what did I do? Sadly, debugger and console.log.
You must have some idea, or ideas, as to where the problem lies, so just start at wherever you are certain your code is working and add a console.log (if you can still see the logs up to the crash) or a debugger (if you can't) to every point along the way to the crash. Eventually you won't make it to one of your debugging statements, and then you'll know that the problem is in-between that statement and the previous one.
It's a really lame way to debug, I know, and as you said you will have to add a lot of debugging statements, but sometimes it's all you have.
This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
How do you debug Javascript applications?
When there's a bug in my javascript .js file, no error is indicated, and the file just does not load.
Is there a fast way to debug something like this?
I have to temporarily delete half the file, test it, delete another half, test it, and so on until I isolate the problem.
How can I display the error when javascript loads the page?
Firebug.
You can see if the file isn't being retrieved in the Net tab.
You can debug it and even add breakpoints in the Script tab.
You can view any errors/warnings in the Console tab.
Try using the firebug pluggin for firefox.
You can put break point and use the step by step debug mode.
Realy helpfull.
Get a js debugger for your browser: firebug if you use firefox. Chrome & Safari have builtin inspectors that do the same thing. IE as usual is more awkward. You should also check your js at jslint.com, although it gives lots of warnings you can ignore.
For Firefox: use Firebug
For Chrome: use the console
For IE: you're screwed. (place alert()s throughout your code and narrow down between the one that was called and the one that was not)
While there are many of versions of IE, this answer applies to IE 7, which is still what the majority of large corporations and government agencies use. Sure, there are workarounds, especially if you have Visual Studio, but question did not specify a browser in the first place.
IE7 has no console, thus the users is screwed and must inject his/her JS with alert()s or use a third-party tool.
I have a big (probably) javascript problem.
i have a long and complex script on the page based on mootools framework,
in FF and other browser everything works fine, but in ie 6 and 7 i got "error:153 (sometimes 84) Unspecified error" and the strange thing is in IE8 that show me the error "Object doesn't support this property or method".
someone know the possible cause of the problem? o maybe someone know a list of IE's unsupported property or method?
In IE8 you can get the line number of the error, then right-click -> view source. IE8 has a proper source, which includes script lines, so you should quickly be able to find the source of your error.
If the script you're using isn't obfuscated or all on one line, you could use the JavaScript debugger in IE8 to pinpoint the object which is causing the error. Press F12 to open the Developer Tools, go to the Script tab, and click the "Start Debugging" option. If there's an error it may well break on the relevant line. If not you can set some breakpoints and step through the code.
You can also use IE8 developer tools http://blogs.msdn.com/ie/archive/2008/09/03/developer-tools-in-internet-explorer-8-beta-2.aspx to debug.
For other version I suggest you use Web developer tool bar which is similar to web developer tool bar for firefox.
Its near impossible to tell what the problem is with this information (at least for me).
For IE6/7 I suggest adding a few alerts to the javascript in intervals to find out exactly what line of code is causing your problem. If you know which object is causing the error, it is usually quite simple to find out what the exact problem is.
IE8 provides nice debugging tools, so that is a good place to start.
In my case the error was due to a $ mapping conflict.
Using jQuery instead of $ solved the issue.
I need to debug JavaScript in Internet Explorer 7.
Unfortunately, its default debugger doesn't provide me with much information. It tells me the page that the error showed up on (not the specific script) and gives me a line number. I don't know if that is related to my problem.
It'd be nice if it could narrow down the error to a line number on a specific script (like Firebug can).
Is there an addon to debug JavaScript in IE7 like Firebug does in Firefox?
Thank you!
See also:
Does IE7 have a “developer mode” or plugin like Firefox/Chrome/Safari?
Web Development Helper is very good.
The IE Dev Toolbar is often helpful, but unfortunately doesn't do script debugging
The hard truth is: the only good debugger for IE is Visual Studio.
If you don't have money for the real deal, download free Visual Web Developer 2008 Express EditionVisual Web Developer 2010 Express Edition. While the former allows you to attach debugger to already running IE, the latter doesn't (at least previous versions I used didn't allow that). If this is still the case, the trick is to create a simple project with one empty web page, "run" it (it starts the browser), now navigate to whatever page you want to debug, and start debugging.
Microsoft gives away full Visual Studio on different events, usually with license restrictions, but they allow tinkering at home. Check their schedule and the list of freebies.
Another hint: try to debug your web application with other browsers first. I had a great success with Opera. Somehow Opera's emulation of IE and its bugs was pretty close, but the debugger is much better.
you might want to try
microsoft script debugger
it's pretty old but it's quite useful in the sense if you stumble on any javascript error, the debugger will popup to show you which line is messing up. it could get irrating sometimes when you do normal surfing, but you can turn if off.
here's a good startup on how to use this tool too.
HOW-TO: Debug JavaScript in Internet Explorer
I've found DebugBar.
Not as good as Firebug, but close.
In IE7, you can bring up firebug lite for the current page by pasting the following in the address bar:
javascript:var firebug=document.createElement('script');firebug.setAttribute('src','http://getfirebug.com/releases/lite/1.2/firebug-lite-compressed.js');document.body.appendChild(firebug);(function(){if(window.firebug.version){firebug.init();}else{setTimeout(arguments.callee);}})();void(firebug);
See http://getfirebug.com/lite.html.
Microsoft Script Editor is indeed an option, and of the ones I've tried one of the more stable ones -- the debugger in IE8 is great but for some reason whenever I start the Developer Tools it takes IE8 a while, sometimes up to a minute, to inspect my page's DOM tree. And afterwards it seems to want to do it on every page refresh which is a torture.
You can inspect contents of variables in Microsoft Script editor: if you poke around under Debug > Window you can turn on local variable inspection, watching etc.
The other option, Visual Web Dev, while bulky, works reasonably well. To set it up, do this (stolen from here):
Debugging should be turned on in IE. Go into Tools > Internet Options > Advanced and check that Disable Script Debugging (Internet Explorer) is unchecked and Display a notification about every script error is checked
Create a new empty web project inside of VWD
Right-click on the site in the Solutions Explorer on the top right, go to Browse With and make sure your default browser is set to IE (it's reasonable to assume if you're a web developer IE is not your default browser in which case that won't be the default.. by default)
Hit F5, IE will open up. Browse to the page you want to debug.
VWD will now open up any time you have a script error or if you set a breakpoint in one of the JS files. Debug away!
UPDATE: By the way, if you experience the same slowdowns as me with IE8's otherwise decent debugger, there is a workaround -- if you encounter or make IE encounter an error so that it pops up the "Do you want to debug" dialogue and hit Yes, the debugger will come up pretty much instantly. It seems like if you go "straight" into debugging mode the Dev Tools never inspect the DOM. It's only when you hit F12 that it does.
IE8 has much improved developer tools. Until then it's best to write javascript for firefox first and then debug IE using alert() statements.
Microsoft Script Editor can be used to debug Javascript in IE. It's less buggy than Microsoft Script Debugger but has the same basic functionality, which unfortunately is pretty much limited to stepping through execution. I can't seem to inspect variables or any handy stuff like that. Also, it only shipped with Office XP/2003 for some bizarre reason. More info here if you're game.
I downloaded the Visual Web Developer 2008 Express Edition mentioned by Eugene Lazutkin but haven't had a chance to try it yet. I'd recommend trying that before Script Editor/Debugger.
It's not a full debugger, but my DP_DEBUG extensions provides some (I think) usful functionality and they work in IE, Firefox and Opera (9+).
You can "dump" visual representations of complex JavaScript objects (even system objects), do simplified logging and timing. The component provides simple methods to enable or disable it so that you can leave the debugger in place for production work if you like.
DP_Debug
The IE9 developer tools worked for me. Just set the "Browser Mode" menu item to IE7.
Hey I came across the same problem and found this the application IETESTER. It's pretty awesome, it's an app that has IE 5.5,6, and 7 bundled into it. It doesn't matter what IE version you currently have. This allows you to have multiple versions side by side.
If you enable javascript debugging in IE options and have Visual Studio installed you can even debug the javascript in VS with all the debug options available to you(watches, conditional breakpoints ,etc.)
If you want to start debugging before an error occurs you simply have to put the line
debugger;
into your JS code and this bring you into VS to begin debugging after this statement.
This is absolutely amazing to me for testing backward compatibility for JS code.
Use Internet Explorer 8. Then Try the developer tool.. You can debug based on IE 7 also in compatibility mode
FireBug Lite:
http://getfirebug.com/firebuglite
The answer is simple.
Get Internet Explorer 9
Press F12 to load up Developer Tools
Switch the browser mode to IE7
Running your code through a Javascript static analysis tool like JSLint can catch some common IE7 errors, such as trailing commas in object definitions.
IE8 Developer Tools are able to switch to IE7 mode
If you still need to Debug IE 7, the emulation mode of IE 11 is working pretty well.
Go to menu: Dev Tools, then to emulation and set it.
It also gives error line information.
The following tools works great for me:
1) http://www.debugbar.com/
Provide a convenience UI to with feature like source, style, DOM, Script, HTML check. It also show the actual error in your JS file (which line, which file).
2) http://www.my-debugbar.com/wiki/CompanionJS/Installing
Provide a console for IE6 or IE7 ( which originally does not support)
Screenshot