If I am using many js files in my project and get JavaScript errors in IE 6 or 7's status bar, then how can I trace, find and solve those errors in Firefox? I know how to trace a problem in IE with visual studio but can we identify area of problem using Firefox?
For Internet Explorer use the Developement Tools of Internet Explorer 8 (press F12).
Internet Explorer 8 supports the Internet Explorer 7 engine.
However Firebug is easier to use and much more powerful!
use firebug.
I would recommend using Firebug (http://getfirebug.com/). It's a plugin for Firefox and does a great job of reporting errors to you. It also has a javascript debugger and a great DOM viewer - both of which are very helpful in fixing scripting bugs.
Web Developer for FF [https://addons.mozilla.org/en-US/firefox/addon/60] can be helpful if you are interested in looking at warnings and other code errors that don't necessarily trigger errors - at least in FF.
Cleaning up your code using this or other tools like JSLint [http://www.jslint.com/] will make your code more manageable in the long run. But in the end, each browser's JavaScript engine just behaves differently, and errors in one specific browser will ultimately have to be debugged in its own environment.
One such error that can you scratching your head even between versions of IE is the misformed object below:
var myObj = {
1 : "val1",
2 : "val2",
}
alert(myObj);
In IE8 and all other major browsers the extra comma after the last entry is overlooked. IE6 and 7 will throw an error. But the Web Developer plugin for FF shows the following warning:
Warning: trailing comma is not legal in ECMA-262 object initializers
Source File: http://localhost/test.html
Line: 10
Source Code:
}
Related
I am looking for a good IE javascript debugger, i have used firebug lite but it seems not so explicit like the real firebug about js errors.
How to know the js errors in internet explorer with exact line number and js file name?
please help.
There is. If you hit F-12 in later versions of IE, you'll get IE's dev tools. They're nowhere near as good as what's in Chrome or FF, but you can check ajax requests, inspect the dom, inspect and set breakpoints in JavaScript code, and even emulate previous versions of IE.
I'm developing in Javascript for quite a long time now. Usually when I hit an error in IE I know roughly where it originated even if the message received from IE is useless bunch of text. When I don't know where the error originated, I usually try to "delete" parts of my code, until the error doesn't repeat itself, and that start manually checking line by line until I find the error.
I'm sure that it's far from the best approach, so I'd like to ask you how you debug error like these:
If you are using IE8+, you can press F12 on a page to open the Developers Tools.
This contains a JavaScript debugger, much like Firebug & Chrome Dev Tools
EDIT:
In response to the comment under the question, if IE is throwing a cryptic error that you are unsure of, there is a couple of steps I would do.
Is it an IE only error? Does the same error occur in Firefox? Chrome?
Is the error occurring in a 3rd party library. If you believe it is, use an un-minified version of the library.
Can you replicate the error outside of your website? Can you make the error occur in a http://jsfiddle.net/ for instance?
If you still can't narrow down the issue, post a question on SO with your code, any error messages, and expectations of the result.
HTH
Try using non-minified version of jQuery - it will give you a better idea where exactly the error is. Also, if you use VS 2010 to debug your js code in IE, it will break at the error line. This always works fine for me.
IE is the only browser that I've managed to successfully use the fantastic Visual Studio script debugger with - in my experience Visual Studio is hands down the best script debugger out there, so quite often I find myself in the reverse situation to you (running broken scripts in IE just so I can use the script debugger)
See How to debug JavaScript in Internet Explorer for instructions on how to use Visual Studio Express to debug scripts in IE - if you own a full edition of Visual Studio then its much simpler (just attach to IE as normal).
I am trying to figure out why a page is not working correctly in Internet Explorer 7.
I get a JavaScript error that says
error is on line 1958 char 7
My HTML code is only 534 lines with all of my JavaScript code externally linked.
How do I go about finding this error?
Does this error put all of the external files in the file which makes the number of lines more than my HTML code?
Would this be what I need to do to figure out where the error is in the JavaScript code?
You should use Internet Explorer Developer Toolbar. It is extremely useful for debugging JS in IE.
I've also heard good things about Web Development Helper. (It even supports IE6!)
If you have Visual Studio, I would enabling script debugging in Advanced options. That may yield better debugging.
My first instinct would be to try the site in Firefox and have a look at it with the Firebug plugin. I'm not sure what kind of debugger support is available in IE.
After installing Internet Explorer Developer Toolbar
window.onerror = function myErrorHandler(errorMsg, url, lineNumber) {
debugger;
console.log(errorMsg, url, lineNumber);
};
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
I have a few scripts on a site I recently started maintaining. I get those Object Not Found errors in IE6 (which Firefox fails to report in its Error Console?). What's the best way to debug these- any good cross-browser-compatible IDEs, or javascript debugging libraries of some sort?
There's no cross-browser JS debugger that I know of (because most browsers use different JS engines).
For firefox, I'd definitely recommend firebug (http://www.getfirebug.com)
For IE, the best I've found is Microsoft Script Debugger (http://www.microsoft.com/downloads/details.aspx?familyid=2f465be0-94fd-4569-b3c4-dffdf19ccd99&displaylang=en). If you have Office installed, you may also have Microsoft Script Editor installed. To use either of these, you need to turn on script debugging in IE. (uncheck Tools -> Internet Options -> Advanced -> Disable Script debugging).
You could also use Firebug Lite - which will work in IE & Opera. It's an external lib that will help you track down problems. It's sometimes more convenient than dealing with the MS Script Debugger.
Firebug
It's only for firefox but it should let you figure out what's happening on IE especially once you have the script line numbers.
You can use Visual Studio and enable debugging in browser
You can install FireBug plugin for Firefox, it's really good!
You can try to install IE8 beta 2 and use it in compatibility mode with built-in debugger.
Also in any line of your JS code you can write
debugger;
and this will be threated as breakpoint for any of the debug tools you use.
Cheers!
Aptana Studio provides JavaScript debugging for Firefox and IE
Firebug is the best all around client-side debugger. I frequently use it to debug CSS code as well as javascript. It allows you to easily find offending areas of code. I especially like the ability to modify tag attributes in the firebug pane and see the effects immediately before committing. Very useful for anyone designing websites.
You could use this tool apparently - Microsoft Script Debugger
Personally I try to go through the code and figure out what's going on - it gives you the line number where it goes wrong right?
To make the Microsoft Script Debugger more user friendly (and to add javascript error messages that actually are helpful to IE), I highly recommend Companion.JS.
Firebug seems to be the most useful so far. When a page is running on firebug, it can be very handy to log messages into firebug via javascript calls to console.log('your log message'); but don't execute that code in IE since the console object is only in scope when firebug is running.
For IE, other folks have mentioned the Script Debugger. Although it is not primarily for javascript debugging, it can be useful to also add the IE developer toolbar, which allows you to easily and dynamically inspect the style and other properties of your page's DOM.
In response to mopoke, for IE6 you definitely want to use Visual Studio for debugging if you can get it. For all intents and purposes, the MS script debugger is useless. You're better off using some form of tracing (not alerts) than using the MS script debugger. Dojo Toolkit, for instance, provides a debug console for tracing, but you can write your own by dumping messages to a secondary window or div.
The script debugger needlessly prompts you on each error in IE6 and even then doesn't give you enough state context to make it useful in a sufficiently complex JS app. Visual Studio is more tightly integrated and much friendlier. Just my experience.