With respect to HTML/web .... The_principles_of_unobtrusive_JavaScript
points out that in some cases there won't be any JavaScript support.
Do such environment - without JavaScript still exist or this is an old article ?
The article you posted is long. It does cover many practices that are good to use today. I wanted to address a few statements the article made on assumptions.
Assumption: everybody’s browser supports JavaScript. Not true: In
order to be unobtrusive to users, taking away the script should not
preclude them from using your site, even though their interaction will
be far less rich than that of users whose browser does support
JavaScript.
All major browsers such as Chrome, Safari, IE, Firefox, and Opera support Javascript. Users may manually disable it, but you can assume most of your users will have Javascript. However, you can use a <noscript> tag as a precaution for users that do not have Javascript running. The data in The <noscript> tag will only be displayed if javascript is not running.
Assumption: all browsers work the same. Not true: In order to be
unobtrusive to browsers, your script should steer clear of plain
errors and compatibility problems, and take special devices such as
speech browsers or mobile phones into account.
All browsers do not work the same. You need to be careful with Javascript and CSS (style) to support all the major browsers. Certain functions may be depreciated or unsupported in some browsers.
Assumption: everybody else will understand my code. Not true: In order
to be unobtrusive to fellow programmers, your script should consist of
clear, clean code and feature a lot of comments to say what your code
is (supposed to be) doing.
You should always try to make your code affective and clear.
Related
I was looking at a "best practices" guide in relation to the inclusion of javascript in web pages (dynamic and static) which suggested that developers should always comment out javascript due to older browsers being unable to support the scripting language.
Is this true?
I tried searching for issues surrounding compatibility but could find nothing - I'm wondering if the information is out of date, as I've never heard of browsers having no idea what scripting is; a separate issue from javascript being deliberately disabled.
By "any" I obviously mean any non-discontinued browser.
Partial duplicate: What web browsers do not support Javascript? and how to identify which browser is client using?
Javascript is widely available, but there are some cases where you cannot rely on its presence.
First of all, the NoScript extension has been pretty successful - I'm not sure if it is still widely used, but you can except that at least a small portion of your users will use it (even if they whitelist your website later).
Another thing to keep in mind is that some browser just cannot implement a good Javascript engine. The best example which comes to mind is TTY-related browsers such as lynx.
Finally, don't forget that some people here are disabled, such as blind peoples, and have to use very specific browsers, which probably cannot work very well along Javascript.
[edit] About the specific "developers should always comment out javascript due to older browsers being unable to support the scripting language" question, I assume you're referencing the following pattern :
<script>//<!--
Actual source code here
//--></script>
Afaik, every modern browser knows what a script tag is, even if they ignore it. I'm not aware of any browser which prints script tag contents.
Let's say I outsource the development of an HTML/JS/CSS/AJAX web app targeting ONLY modern browsers. If it matters, assume there are 20 unique templates used in creating the application (to give an idea of the size of this application). My understanding is that much time/money is spent hand tweaking the code to make it consistent among browsers. I'm interested in ways to minimize this expense.
As of June 2011, Google Chrome Frame is advertised to not require administrator privileges for the user to download and install for IE 6-9, which essentially runs Chrome as a plug-in inside IE to avoid browser incompatibility issues with IE (substituting potential compatibility problems with Chrome, which should be much less than IE).
If I were to direct the developers to target only modern browsers minus IE, requiring all IE users to download Chrome Frame instead, would this path translate into any significant development cost/time savings? (My users are engineers and may be willing to accept this tradeoff since this application is not offered elsewhere.) I just don't have a feel for how much effort is made for IE versus other (modern) browsers, and wondered if anyone with experience could comment whether this makes cents (pun intended) or is simply crazy.
Also, any downside to doing this?
You will save time and money. I have done something similar for our in-house application. The site runs only on webkit browsers (chrome and safary).
We save a log of time, because the css and JavaScript can be more efficient, and most importantly, we do not have to test every change on 6 different browsers. This is very liberating.
If your users allow you to exclude IE, i recommend it.
It all depends on your application and developers. With enough knowledge it's possible to write code without even checking in IE until the end but only keeping it in mind and have 99% of things as expected in ie8-9, 80% in ie6-7.
If your users are engineers I can hardly imagine them using ie in the first place and even if so definitely not ie6/7.
Even if you don't go with Chrome-frame, given above points, if you're willing to go with slight to mild visual design degradation you can get away without specifically targeting ie...
Here's a little ie9 promo for ya :)
http://varonasf.com/ie69/
(only works in decent browsers)
This is the design decision behind Google Frame. You always have the choice of either designing for the lowest common denominator, i.e. IE6, and having a limited function site, or designing for a reasonable HTML 5 standard and forcing users to upgrade.
...allowing users to access modern web technologies like HTML5 on
legacy browsers.
http://blog.chromium.org/2010/09/google-chrome-frame-stable-and-speedy.html
Years ago I used to design with JavaScript disabled browsers in mind. How important is it nowadays?
Is it really something you need to worry about? I've never come across a user in real life who has JavaScript disabled. Anyone got any figures?
Having had my own company for a year and working at another for a couple of years, none of my direct clients has ever had JavaScript disabled, in one single instance I've had one of my clients customers have JavaScript disabled, so my current guess (purely anecdotal evidence) is about 1/50.000.
My biggest worry when working with JavaScript is and has always been cross browser compliance, what works in FF doesn't always work in Chrome, what works in FF and Chrome doesn't always work in IE 8, and what works in all of the above... doesn't always work in IE 7.....
And then there is IE 6.
Edit, yay data:
By July 31, 2009 firefox had 1 billion downloads
Noscript has as of September 14, 2010 73 million downloads
That tells us that about 7% of the times FF users has downloaded the browser, they have also installed the noscript plugin.
Edit addendum
Making this community wiki, add your math people.
Edit:
In October 2010, Yahoo! published actual stats.
In short, the answer varies by country, but for a US site, you can expect 2% of your users to have javascript disabled.
My tips would be:
Designing a site with a fallback to no JS is usually entirely possible and not all that difficult. You should consider doing it, regardless of what the statistics about JS-disabled browsers say.
However, don't let this stop you from being creative. If you must rely on JS and there's no workaround, don't hesitate. If someone wants full browsing experience and works with JS off, it's his/her fault.
Encoding emails using JS unescape() is always a good idea. In a JS-disabled browser, just display nothing.
You're right: straight up disabling of Javascript is pretty uncommon these days because it is used by so many sites.
However most browsers have more fine-tuned control; ie to turn it on/off per site, which may still be used by paranoid.. uh, security-conscious users.
Even more likely, there's a Firefox extension called NoScript which is actually very popular. This extension gives the user even more control over when to allow Javascript. I don't know whether there's similar plug-ins for other browsers, but I expect so.
Finally, many disabled users will be running screen-readers or other accessibility browsers which may still not run Javascript properly/at all. If you want to support these users, then you'll need to be aware of the unique environments they work in.
So yes, it is still a good idea to support non-JS users, even if they are in the minority. That said, I don't think you need to make everything work for them, as long as your basic site functionality works (ie add to basket, checkout, etc), there's no need to get too stressed about them not getting the bells and whistles.
The NoScript plugin for Firefox has been downloaded 73,063,406 times.
Your site should be usable without JS (so don't replace links with JS voodoo unless you absolutely have to).
Also people that need special output devices (like Braille Readers) will prefer sites that that work without JS.
I agree that disabling javascript is uncommon and i also agree that it's important to build websites while taking javascript-disabled browsers in mind.
BUT javascript is strongly invloved in modern & large websites now (google, youtube, facebook). without javascript you can't build AJAX supported websites and you can't also use the power of jQuery or any js library.
and if you are worry about cross browser compliance, you might wanna consider using jQuery because it abstracts away the famous cross-browser issue.
personally, i'll be always using javascript in any website i build :).
I'm a bit late to the party, but about a month after this question was asked, Yahoo! published actual stats.
In short, it depends on where your visitors are from, but in the US, you can plan on about 2% of your visitors having javascript disabled.
Here's a couple of general guidelines. People who use different browsers with accessibility in mind, or run in a terminal with no graphics toolkit (text based) are most likely to not run JavaScript. If you want to cater to these people, all you need to do is use JavaScript if you want, but only use it to enhance, not provide the content.
By this, I mean, for example, you can enhance a table by adding sort controls with JavaScript, but don't use JavaScript to parse a data file and create the table. Use a server-side program to handle a database or data file instead.
However, there becomes a grey area, and this all has to do with what kind of user base you are targeting. If you are writing a Chrome experiment then by all means, write it all in JavaScript; it's about the JavaScript.
If, however, your website aims to provide information, it's best to avoid using JavaScript to provide content wherever possible; only enhance it.
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/
I have developed a html file. It is working fine in IE6 and IE7. When I run the same html file in IE8, the design is not the same and the Javascript is not working properly. It is showing browser's "Compatibility view"?
How do I fix this?
It is difficult to really help you as you are not giving us enough information. Your question is very broad in the sense that getting your website to display the same in all browsers is a lot of work and the reasons why a particular layout is not working in a particular browser are just about infinite.
A few important things to get you started on your journey, though:
Use a DOCTYPE or you'll throw browsers into quirks mode.
Reset your CSS so you can apply the styles you want to elements.
Use a Javascript library - the popular one around these parts is jQuery, and it is the one I personally recommend. However, it doesn't really matter which one you go with as long as you use one. A lot of smart guys have put a lot of hours into taking care of all the incompatibilities between browsers. Trying to do a lot of dynamic stuff on your website with pure Javascript is bordering on masochistic.
Once I started doing these things, making my site work the same across browsers got a whole lot easier.
Give this a read, it details the things that cause IE8 to switch to compatibility mode, and how to fix them.
http://blogs.msdn.com/ie/archive/2009/03/12/site-compatibility-and-ie8.aspx
You must give us some example codes (or even working website) and do something like:
Website validation (html markup, css and javascript)
Test it on another modern browser (opera, firefox, chrome, safari, etc)
Do you adhere to web standard when building web?
Do you rely on CSS hacks?
Did you know that Trident rendering engine on IE6 & IE7 didn't even pass ACID 2 test? which mean have a lot troubles with CSS implementation...
Then we might be can help you