问题
I'm building a site right now, so far I've painfully forced everything to be compliant and it looks pretty much the same across browsers. However, I'm starting to implement some third party/free javascripts which do things like add attributes (eg. order=2). I could work around this but it's a pain, and I'm starting to lose my principals of making sure everything is valid. Really, is there any point to working around something like this? I got the HTMLValidator plugin for firefox, and looking at most major sites (including this one, google, etc.), they aren't valid XHTML or HTML.
回答1:
I have yet to experience an instance where the addition of a non-standard attribute has caused a rendering issue in any browser.
Don't try to work around those non-standard attributes. Validators are handy as tools to double check your code for unintentional mistakes, but as we all know, even fully valid xhtml will not always render consistently across browsers. There are many times when design decisions require us to use browser specific (and non-standard) hacks to achieve an effect. This is the life of a web developer as evidenced by the number of technology driving sites (google, yahoo, etc.) that do not validate.
回答2:
The validation is useful to determine when things are failing to meet standards you presumably agree with. If you are purposefully using a tool that specifically adds something not in the validation standards, obviously that does not break your personal standards agreement.
This discussion gets much more difficult if you have a boss or a client who believes everything should return the green light, as you'll have to explain the above to them and convince them it's not simply you being lazy.
That said, be sure it's not simply be a case of you being lazy. While the validators may annoyingly constantly bring up every instance of the third party attribute, that doesn't invalidate (ha) the other validation errors they're mentioning. It's often worth scanning through as a means of double-checking your work.
回答3:
Standards compliance is about increasing the chance that your page will work in the browsers you don't test against. This includes screen readers, and the next update of the browsers you do test against, and browsers which you do test against but which have been configured in unexpected ways by the user.
Validating doesn't guarantee you anything, since it's possible for your page to validate but still be sufficiently ambiguous that it won't behave the way you want it to on some browser some day.
However, if your page does validate, you at least have the force of the XHTML spec saying how it should behave. If it doesn't validate, all you have is a bunch of informal conventions between browser writers.
It's probably better to write valid HTML 3 than invalid XHTML, if there's something you want to do which is allowed in one but not the other.
回答4:
If you're planning on taking advantage of XHTML as XML, then it's worth it to make your pages valid and well formed. Otherwise, plain old semantic HTML is probably want you want. Either way, the needs of your audience outweigh the needs of a validator.
回答5:
Just keep in mind that the XHTML tag renders differently in most browsers than not having it. The DOCTYPE attribute determines what mode the browser renders in and dictates what is and isn't allowed. If you stray from the XHTML compliance just be sure to retest in all browsers.
Personally I stick with the latest standards whenever possible, but you have to weigh time/money against compliance for sure and it comes down to personal preference for most.
回答6:
As far as browsers are concerned, XHTML compliance is pointless in that:
Browsers don't have XHTML parsers. They have non-version-specific, web-compatible HTML parsers that build a DOM around the http://www.w3.org/1999/xhtml namespace.
Some browsers that have XML parsers can treat XHTML markup served as application/xhtml+xml as XML. This will take the XML and give default HTML style and behavior to elements in the http://www.w3.org/1999/xhtml namespace. But, as far as parsing goes, it has nothing to do with XHTML. XML parsing rules are followed, not some XHTML DTD's rules.
So, when you use XHTML markup, you're giving something alien to browsers and seeing if it comes out as you intend. The thing is, you can do this with any markup. If it renders as intended and produces the correct DOM, you're doing pretty good. You just have to make sure to keep DOCTYPE switching in mind and make sure you're not relying on a browser bug (so things don't fall apart in browsers that don't have the bug).
What XHTML compliance is good for is syntax checking (by validating) to see if the markup is well formed. This helps avoid parsing bugs. Of course, this can be done with HTML also, so there's nothing special about XHTML in this case. Either way, you still have to test in browsers and hope browser vendors make awesome HTML parsers that can accept all kinds of crap.
What's not pointless is trying to conform to what browsers expect. HTML5 helps with this big time. And, speaking of HTML5, you can define custom attributes all you want. Just prefix them with data-, as in <p data-order="This is a valid, custom attribute.">test</p>.
回答7:
Being HTML Valid is usually a help for both of you and the browser rendering engine. The less quirks the browsers have to deal with, the more they can focus on adding new features. The more strict you are, the less time you'll spend time wondering why this f@#cking proprietary tag does not work in the other browsers.
On the other hand, XHTML is, IMHO, more pointless, except if you plan to integrate it within some XML document. As IE still does not recognize it, it's pretty useless to stay stick with.
回答8:
I think writing "valid code" is important, simply because you're setting an example by following the rules. If every developer had written code for Fx, Safari and Opera, I think IE had to "start following the rules" sooner than with version 8.
回答9:
I try write compliant code most of the time weighing the time/cost vs the needs of the audience in all cases but one. Where you code needs to be 503 compliant, it is in your best interest and the interest of your audience to write compliant code. I've come across a bunch of screen readers that blow up when the code is even slightly off.
Like the majority of posters said, it's really all about what your audience needs.
回答10:
It's not pointless by any means, but there is plenty of justification for breaking it. During the initial stages of CSS development it's very useful for diagnosing browser issues if your markup is valid. Beyond that, if you want to do something and you feel the most appropriate method is to break the validation, that's usually ok.
An alternative to using custom attributes is to make use of the 'rel' attribute, for an example see Litebox (and its kin).
回答11:
Sure, you could always just go ahead and write it in the way you want, making sure that at minimum it works. Of course, we've already suffered this mentality and have witnessed its output, Internet Explorer 6.
I am a big fan of the Mike Davidson approach to standards-oriented development.
Just because you can validate your code doesn’t mean you are better than anybody else. Heck, it doesn’t even necessarily mean you write better code than anybody else. Someone who can write a banking application entirely in Flash is a better coder than you. Someone who can integrate third-party code into a complicated publishing environment is a better coder than you. Think of validation as using picture perfect grammar; it helps you get your ideas across and is a sign of a good education, but it isn’t nearly as important as the ideas and concepts you think of and subsequently communicate. The most charismatic and possibly smartest person I’ve ever worked for was from the South and used the word “ain’t” quite regularly. It didn’t make him any less smart, and, in fact, it made him more memorable. So all I’m saying is there are plenty of things to judge someone on… validation is one of them, but certainly not the most important.
A lot of people misunderstand this post to mean that we shouldn't code to standards. We should, obviously, but it's not something that should even really be thought about. The validation army will always decry those that do not validate, but validation means so much more than valid code.
So, don't lose your principles, but remember that if you follow the standards you're a lot less likely to end up in the deep-end of issues in the future. The content you're trying to provide is far more important than how it is displayed.
来源：https://stackoverflow.com/questions/101822/is-xhtml-compliance-pointless