I want to determine the best javascript framework to use in order to maintain IE 6 compatibility.
Specifically I want to know which best supports IE6 - Dojo or JQuery.
I determine compatibility based on the amount of work you have to do to make the framework work with IE6 (framework may have features that need special coding to enable them to work with IE6, or there may be features that are incompatible altogether).
Are there any benchmarks, or compatibility matrices, for the various javascript frameworks that quantify the work you would have to do to maintain IE6 compatibility?
Both jQuery and DOJO claim they support IE6:
http://docs.jquery.com/Browser_Compatibility
http://o.dojotoolkit.org/support/faq/what-browsers-does-dojo-support
DOJO does seem to have quite a grandiose claim:
... 100% of the available
functionality works, that
accessibility is handled correctly,
and that all internationalization and
localization is supported. This is a
very high bar, ...
And jQuery claims they test regularly in IE6.
Personally, I would let other requirements dictate which framework you use. One of the fundamental jobs for a JavaScript library is to be cross browser compatible, so any decent library is going to be good at it.
"Better" in your question indicates subjectivity, so I'd probably change this to a community wiki.
The best thing to do in each case is to look at what the libraries say they support. I know that he following frameworks handle IE6 well:
Prototype
jQuery
I don't have up-to-date personal experience with Dojo or ExtJS, but they supported IE6 well a couple of years back when I looked into them — I'd be surprised if they don't still support it (for now). (ExtJS's "learn more" page says IE6 and up; the "supported" list on the Dojo front page is not, shocking, a link to a list.)
The Closure team originally said they supported IE6 (although they have no official list), but that may have changed with Google's recent decision to drop IE6 support from their web apps.
Amongst other things, the main priority of a javascript library is to solve the cross-browser issues. Having said that, I personally use jQuery and yes it overcomes the IE6 issues too other than other later versions of IE.
Related
I'd like to use autofocus="autofocus" in my code, but since some browsers don't support this yet, I was thinking of adding some JS code, which would search for an element with such a tag, and focus it with JS. But since this seems to be a common requirement, I wonder if there are any ready libraries, which can take care of at least some HTML5 annoyances with older browsers?
I believe the correct answer would be not quite. Modernizr 2.0 (including html5shim) gives us semantic elements of html5 (actually the html5shim does that) and great feature detection which you can use for graceful js fallback.
In you case It would be using jQuery .focus() with something like:
if (!Modernizr.autofocus){
$('input[autofocus=""]').focus();
}
more examples here
If older browsers don't support certain advanced features, then I would say follow progressive enhancement and don't worry about it. So long as the core functionality of your site—ordering products, or whatever—works across the board, then don't be afraid to add in shiny html5 features for the benefit of your users with good browsers.
Putting in clunky/third-party code to force IE6 and 7 to behave in a civilized manner will potentially be a lot of work for you, will be prone to bugs, and won't even give you too much of a payoff since the folks using IE6 probably won't be looking over the shoulders of Chrome users to see a nicer version of your site there.
Here are the slides (from a jQuery conference) that really drove this home for me.
The role of Modernizr (previously mentioned) is to do feature detection, to determine what HTML 5 features are available. Modernizr doesn't automatically make unavailable HTML 5 features available, but it does make it possible for you to conditionally load scripts (commonly referred to as polyfills) to add those features. In the case of autofocus, the html5support library should provide what you need, and you can use Modernizr's conditional loading to only load it if needed.
Users of libraries like jQuery say that they implement such a features.
I don’t recommend it anyway, try to code the minimum functions you need by yourself.
Take also a look at http://www.modernizr.com/.
In Coders at work, Douglas Crockford discusses how bugs in browsers cause Javascript to be a complex, clunky language and fixing it is a catch-22. In Beginning JavaScript with DOM scripting and Ajax Christian Heilmann says something similar "[The] large variety of user agents, of different technical finesse [...] is a great danger to JavaScript."
Why doesn't JS have a breaking new version? Is there something inherent n the language design where backwards compatibility becomes a must?
Update
Why can't javascript run with multiple engines in parallel? Similar to how .NET runs versions 2, 3 and 4 on the same machine.
Lazy copypasta at OP's request:
JavaScript is just a programming language: syntax and semantics. It has no built-in support for browsers (read: the browser DOM). You could create a JS program that runs outside of a browser. You (should) know what an API is - the DOM is just a JavaScript API for manipulating an HTML page. There are other DOM APIs in other languages (C#, Java, etc.), though they are used more for things like XML. Does that make sense?
Perhaps this MDC article can clarify further.
Well a breaking change would break a lot of existing websites, which would make a lot of people very angry :)
Backwards compatibility is important because of the large number of browsers deployed and the wide variety of versions of those browsers.
If you serve a new, incompatible kind of Javascript to old browsers, they all break.
If you invent a new language that is not considered to be Javascript by existing browsers, then it doesn't work with the majority of browsers. Very few users will be willing to download a new browser just to work with your new language. So web developers have to keep writing compatible Javascript to support the majority of the users, no matter how great the new language is.
A lot of people would like to see something better than current Javascript be supported by browsers, but it just isn't going to happen any time soon. All the makers of browsers and development tools would have to support the new thing, and continue to support the old Javascript stuff too. Many interested parties just wouldn't consider the benefit to be worth the cost. Slow evolution of Javascript seems to be the only viable solution.
As a matter of fact, ECMAScript 5 is not fully backwards-compatible for the very reasons you mentioned.
Inertia.
Making a breaking change would break too many sites, no browser vendor would want to deal with all the bug reports.
And PHBs would be against targeting a new version, why should they have their developers write javascript for the broken and the fixed languages? Their developers will have to write it for the broken version anyway so why bother with 2 implementations (which from a developer perspective sucks too since now they have to update, support and debug 2 separate trees).
Ecmascript 5 has a "strict" mode. I think this strict mode is intended to combat the problem you mention. Eventually you'd mark scripts "strict" that you want to use the new engine, all others get run in an old crufty VM, or with un-optimized codepaths or whatever.
This is kind like IE and Mozilla browsers having multiple "modes" of rendering websites (IE even swaps out rendering engines).
See this question about it
Javascript has subtle differences across different browsers. This is because each browser manufacturer has different sets of responsibilities to their users to support backwards compatibility (if any). If I had to pick, I'd say the biggest barrier to the advancement of javascript is older versions of Internet Explorer. Due to service agreements with their users, Microsoft is contractually obliged to support older browsers. Even if other browsers cutoff backwards-compatibility, Microsoft will not. To be fair, Microsoft does realize how terrible their browsers are and will hopefully push IE 9.0 very hard. Despite the inconsistencies of javascript across different browsers, they are subtle enough to make cross-browser programming more than feasible. Abruptly cutting off backwards-compatibility would be a practice that would make web development a nightmare. Incrementally cutting of backwards-compatibility for specific aspects of javascript is feasible.
There is much more else wrong with JavaScript. You can't be fully backwards-compatible with things that were never fully compatible when they were fresh... Say, the length of the array [1,] is reported as 2 by at least older versions of internet explorer.
The biggest fault of JavaScript is that is comes with a tiny, incomplete and pretty much unusable standard library. That is why everyone retreats to using jQuery, Dojo, Mochikit etc. - these offer mostly functionality that should be part of some standard library included with the browsers instead of floating around in thousands of copies and versions. It's actually what makes .NET and Java so popular: the language comes with a reasonable standard library. With C and C++, you have to dig out the nice libraries (Boost e.g.) yourself.
But other than that, the ECMAScript standard occasionally is updated.
Google is also trying to do this bold step forwards and redo JavaScript in a slightly more sane way. The efforts are known as Dart: http://www.dartlang.org/
For all I can tell, Dart largely uses the syntax of JavaScript minus a couple of its quirks. Apart from that, it also is nicer for the virtual machine and will thus likely run faster (unless of course you compile Dart to Javascript and use a JavaScript VM; which is offered as a compatibility option). But of course any hardcore JavaScript nazi^W enthusiast will not like anything that claims to be better than JavaScript. Whereas for me, they don't go far enough. In particular, they still don't provide enough "classpath".
I've been lucky to develop websites for the past 3 years for companies that don't need to support IE 6 in any way.
I've just accepted a development job with a company that works exclusively with IE 6 customers in the financial field. These people may be hemmed in by corporate IT departments or haven't upgraded, or whatever the reason is, we have to support IE 6 (and JUST IE 6).
I have no background in supporting this browser and I used to happily skip over SO questions that dealt with IE lte selectors and all of that. But now that it's going to pay the bills, I want to know as mch as I can about the CSS selectors that work/don't work, how JS may be quirky, and anything else that may help me catch up in the new job.
Is there a good respository of the "quirks" that make up the lovable IE 6 experience, or is it spread piecemeal across the 'tubes?
Is there a good respository of the "quirks" that make up the lovable IE 6 experience
quirksmode.org is an excellent resource for browser compatibility questions. It has great, nicely designed compatibility tables that give you almost everything you need to know. Be sure to take a look.
At hasLayout is an excellent overview of all known IE CSS bugs, most of them complete with solutions. This site is imo better overviewable, a real bug repository. All is summarized in short instead of spread over 100s pages like Quirksmode, which in turn is however excellent as a general reference.
My clients use IE6. The repositories listed above may mention these, but nevertheless I write them here.
If you use https, avoid mixed content messages by avoiding javascript:void(0) and similar constructs.
If you use https, avoid mixed content messages by ensuring all iframes have a valid src attribute.
Find a copy of Microsoft Script Debugger and learn to love it. It stinks, but it seems to be the only game in town.
Ask your company to let you develop using FF and FireBug (I did), develop using these, and test very often in IE6.
I use the following URL to dump the DOM:
javascript:'<xmp>%20+%20window.document.body.outerHTML%20+%20</xmp>'
Quirksmode is an invaluable source of information for this sort of thing.
In particular, take a look at the compatibility tables.
"QuirksMode.org is the prime source for browser compatibility information on the Internet." Specifically, to your question visit the CSS2 page there, and look at the IE6 column on the table.
This is a nice article about the 9 most common IE bugs and how to fix them.
Good suggestions... a couple of things that might help:
"Microsoft Visual Web Developer 2008 Express Edition" is much better than the old "Microsoft Script Debugger": http://www.microsoft.com/express/Web/
There's also Firebug Lite: http://getfirebug.com/firebuglite
A compatibility library for browsers that lack full support for JavaScript 1.6: http://en.wikipedia.org/wiki/MediaWiki:Gadget-JSL.js
MSDN will help too: http://msdn.microsoft.com/en-us/default.aspx
I'm not a JavaScript wiz, but is it possible to create a single embeddable JavaScript file that makes all browsers standards compliant? Like a collection of all known JavaScript hacks that force each browser to interpret the code properly?
For example, IE6 does not recognize the :hover pseudo-class in CSS for anything except links, but there exists a JavaScript file that finds all references to :hover and applies a hack that forces IE6 to do it right, allowing me to use the hover command as I should.
There is an unbelievable amount of time (and thus money) that every webmaster has to spend on learning all these hacks. Imagine if there was an open source project where all one has to do is add one line to the header embedding the code and then they'd be free to code their site per accepted web standards (XHTML Strict, CSS3).
Plus, this would give an incentive for web browsers to follow the standards or be stuck with a slower browser due to all the JavaScript code being executed.
So, is this possible?
Plus, this would give an incentive for web browsers to follow the standards or be stuck with a slower browser due to all the JavaScript code being executed.
Well... That's kind of the issue. Not every incompatibility can be smoothed out using JS tricks, and others will become too slow to be usable, or retain subtle incompatibilities. A classic example are the many scripts to fake support for translucency in PNG files on IE6: they worked for simple situations, but fell apart or became prohibitively slow for pages that used such images creatively and extensively.
There's no free lunch.
Others have pointed out specific situations where you can use a script to fake features that aren't supported, or a library to abstract away differences. My advice is to approach this problem piecemeal: write your code for a decent browser, restricting yourself as much as possible to the common set of supported functionality for critical features. Then bring in the hacks to patch up the browsers that fail, allowing yourself to drop functionality or degrade gracefully when possible on older / lesser browsers.
Don't expect it to be too easy. If it was that simple, you wouldn't be getting paid for it... ;-)
Check out jQuery it does a good job of standardizing browser javascript
Along those same lines explorercanvas brings support for the HTML5 canvas tag to IE browsers.
You can't get full standards compliance, but you can use a framework that smooths over some of the worst breaches. You can also use something called a reset style sheet.
There's a library for IE to make it act more like a standards-compliant browser: Dean Edwards' IE7.
Like a collection of all known
javascript hacks that force each
browser to interpret the code properly
You have two choices: read browser compatibility tables and learn each exception a browser has and create one yourself, or use avaiable libraries.
If you want a javascript correction abstraction, you can use jQuery.
If you want a css correction abstraction, you can check /IE7/.
I usually don't like to use css corrections made by javascript. It's another complexity to my code, another library that can insert bugs to already bugged browsers. I prefer creating conditional statements to ie6, ie7 and such and create separate stylesheets for each of them. This approach works and doesn't generate a lot of overhead.
EDIT: (I know that we have problems in other browsers, but since IE is the major browser out there and usually we need really strange hacks to make it work, css conditional statements is a good approach IMO).
Actually you can,there are lots of libraries to handle this issue. From the start of the time, javascript compliance issue always was a problem for developers and thanks to innovative ones who developed libraries to get over this problem...
One of them and my favorite is JQuery.
Before JavaScript 1.4 there was no global arguments Array, and it is impossible to implement the arguments array yourself without a highly advanced source filter. This means it is going to be impossible for the language to maintain backwards-compatibility with Netscape 4.0 and Internet Explorer 4.0. So right out I can say that no, you cannot make all browser standards compliant.
Post-netscape, you can implement nearly all of the features in the core of the language in JavaScript itself. For example, I coded all methods of the Array object in 100% JavaScript code.
http://openjsan.org/doc/j/jh/jhuni/StandardLibrary/1.81/index.html
You can see my implementation of Array here if you go to the link and then go down to Array and then "source."
What most of you are probably referring to is implementing the DOM objects yourself, which is much more problematic. Using VML you can implement the Canvas tag across all the modern browsers, however, you will get a buggy/barely-working performance in Internet Explorer because VML is markup which is not a good format for implementing the Canvas tag...
http://code.google.com/p/explorercanvas/
Flash/Silverlight: Using either of these you can implement the Canvas tag and it will work quite well, you can also implement sound. However, if the user doesn't have any browser plugins there is nothing you can do.
http://www.schillmania.com/projects/soundmanager2/
DOM Abstractions: On the issue of the DOM, you can abstract away from the DOM by implementing your own Event object such as in the case of QEvent, or even implementing your own Node object like in the case of YAHOO.util.Element, however, these usually have some subtle changes to the standard API, so people are usually just abstracting away from the standard, and there is hundreds of cases of libraries that abstract away.
http://code.google.com/p/qevent/
This is probably the best answer to your question. It makes browsers as standards-compliant as possible.
http://dean.edwards.name/weblog/2007/03/yet-another/
It's the year 2009. Internet Explorer 8 has finally been released, and Firefox is coming up to 3.5. Many of the large browsers are starting to integrate features from CSS3 and HTML 5, or have been doing that for quite a while now. Still, I find myself developing web pages exactly the same way I did back in 2005.
A lot of progress has been made since then, and I think the reason that I haven't started taking advantage of these new possibilities is that it's so hard to know which of the new features that work in all major browsers. Since I'm mostly a backend developer I just don't have the time to keep up these developments anymore. Still, I feel like I'm missing out on a lot of cool stuff that actually would make my life a lot easier.
How can I quickly determine if a feature of CSS3 or HTML5 is supported by all major modern browsers?
Can I Use is a website which tracks browser support for current and upcoming web standards. Check it out if you would like to know whether or not a given feature is widely supported.
Font embedding through CSS, using #font-face. Webkit/Safari has been supporting it since version 3.1, Microsoft since IE4, Mozilla since Firefox 3.5 (browser support overview).
Also, the varied implementations of the Selectors API, which provides a browser-native CSS selector engine for use in DOM scripting.
For other examples, When Can I Use... seems to be a very good reference.
I would say display:table and a range of CSS2.1 selectors are the big wins for designers. display:table solves some unsolvable or difficult layouts like 100% height and inside borders without breaking semantics and using actual tables.
Multiple classes (.c1.c2)
I use min/max-width/height a lot.
Also working :hover and !important are awesome.
I would have liked to add SVG support to that list but naturally Microsoft messed that up.
BTW, big warning to those getting excited about HTML5 features. There is no official date for the adoption of this spec. It's even been implied it could take another 10 years (though I doubt that). The point is anything you do with HTML5 now is subject to breakage when the official spec does arrive and in the meantime you can expect plenty of browser inconsistencies, bugs and API changes (not to mention browsers that don't support the features at all).
Browser support for local storage should enable a bunch of new ideas now that some content can be saved on a user's machine.
Reference docs:
Mozilla Firefox
Internet Explorer