Is there any fallback mechanisms in Ruby on Rails 3.2 and 4.0 when someone has JavaScript disabled?
How would an application react, specifically when using ajax request. Would it fallback to normal requests?
I ask this because I need a website which also can handle requests from text browsers for disabled people.
What are some strategies if there is no default fallback.
See this post. Stop loading the page if Javascript is disabled
In general I can't really think about any fallback mechanism here - note that huge part of requests done by rails are in fact ajax requests, as it is impossible to send PUT or DELETE over (Instead of delete request, rails send ajax post request with data: {"_method"="delete"}).
In short, for me disabling JS will break the page heavily, I'm gona test it today.
I'm not well experienced with RoR, but I suspect this is more a question of how you design your front-end architecture. My limited understanding is that RoR didn't provide any javascript "out of the box"; it's default state is to create views that produce flat HTML, which you can dress up how you like with JS and CSS.
Your HTML should be written such that the user should be able to get to all the content they are most interested in, without having to rely on JavaScript to do it. This means you should only use JS to augment the experience. In the language of common front-end practice, do progressive enhancement.
After some research I found the answer:
Ruby on Rails uses unobtrusive javascript to accomplish this. Any Ajax request will then gracefully "degrade" to a normal POST or GET request if javascript is disabled. The only action that will not be working out of the box is delete since it is the only request that is not fully supported by all browsers natively and needs js.
Find out more about that in that railscast: http://www.youtube.com/watch?v=t_MBLfrKTiE
I have an ASP.NET (VB codebehind) intranet site at work. We have Intermec scanners that we have created web apps for. The IE version on the scanners are "PIE" (Pocket Internet Explorer) which doesn't support AJAX or jQuery. The issue is I need to do several SQL calls in our app w/o post backs. My research tells me that javascript is the best way to go. So I need help confirming that this is possible with JavaScript, and if so how can I accomplish this. Or, find another way to do it inside my "PIE" browser? Mostly I will just be checking strings, but there were will be times I need to get a dataset and display it in a grideview (or tbl) all w/o a post back.
Thanks
Josh
UPDATE \ it appears there is evidence that suggests AJAX is available on PIE devices. So i'm willing to try an AJAX solution.
tks.
If JQuery and AJAX really aren't options, you could always drop an IFRAME on your page, and dynamically alter the IFRAME url to query a different page, then read the page contents using javascript. It's hacky and ugly, but I've seen it work before.
I want to analyse some data of a webpage, but here's the problem: the site has more pages which gets called with a __doPostBack function.
How can I "simulate" to go a page further and analyse this site, and so on..
At this time I analyse the data with JSoup in java - but I'm open to use some other language if it's necessary.
A postback-based system (.NET, Prado/PHP, etc) works in a manner that it keeps a complete snapshot of the browser contents on the server side. This is called a pagestate. Any attempt to manipulate with a client that is not JavaScript-capable is almost sure to fail.
What you need is a JavaScript-capable browser. The easiest solution I found is to use the framework Firefox is written in - XUL - to create such a desktop application. What you do is basically create a desktop application with a single browser element in it, which you can then script from the application itself without restrictions of the security container. Alternatively, you could also use the Greasemonkey plugin to do your bidding. The latter is a bit easier to get started with, but it's fairly limited since it's running on a per-page basis.
With both solutions you then have access to the page's DOM to gather data and you can also fire events (like clicking on a button). Unfortunately you have to learn JavaScript for this to work.
I used an automation library which is Selenium, which you can use in a lot of languages (C#, Java, Perl,...)
For more information how to start this link is very helpful: this.
As well as Selenium, you can use http://watin.org/
I would like to offer viewers a contact form that is modified according to the user's input. An example of such a form is on the Ext JS site.
I have not looked into the product, but I would like to know if there are any other programs/functions that generate such a form dynamically? I found only samples on adding other input elements to existing forms.
Here are some other implementations:
http://neyeon.com/p/jquery.dform/ (depends on jQuery)
http://neyric.github.com/inputex/ (depends on YUI)
http://robla.net/jsonwidget/
I also plan to add this functionality to my own js-forms library, which would also handle validation.
You can always create whatever DOM structure you like using JavaScript. Be it additional inputs or even additional FORM elements. It then depends of course what you use on the server side to process form data and how you do that.
Maybe I haven't understood the nature of your problem because you haven't explained yourself too good.
ExtJS is a JavaScript library that does everything on the client side. It also provides the ability to rapidly create user interface by providing Javascript configuration objects that will result in rich widget creation.
You can do lots with jQuery (and jQueryUI) as well, but it's up to you how to do it. ExtJS just has these very functionally rich and visually consistent set of client controls/widgets that you can use out of the box without much additional development (not to mention bug killing that comes along custom development).
For instance: When writing an Asp.net MVC application it's very easy to issue an Ajax call that would return HTML of so called partial view with complete HTML of your form that you can then easily display in a modal dialog for instance.
If you do need all that functionality to create a desktop-like application I suggest you do take a plunge into ExtJS because it is definitely a very good product. I've used it about 3 years ago (version 2) on some project and I was amazed by the work they've done with it. It's very feature rich product that makes it really easy to create desktop like web applications.
But if you're after a usual web site then a desktop-like experience is probably not what you should give to your visitors.
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I'm building a web application with the Zend Framework. I have wanted to include some AJAX type forms and modal boxes, but I also want my application to be as accessible as possible. I want my application to be enhanced by AJAX, but also fully functional without AJAX.
So as a general guideline...when should I not use AJAX? I mean, should I bother making my application usable without AJAX? Or does everyone have AJAX enabled browsers these days?
If you mean "accessible" in the ADA sense, AJAX is usually a no-no - your site should provide all its content and core functionality using only standard (X)HTML and CSS. Any javascript used should merely extend the core functionality, and your site should be coded to work elegantly in the absence of a javascript-enabled browser.
Examples: if you want a user to click on a thumbnail and get a full-size version of the image as a result, you can make the thumbnail a link. Then, the onclick event will fire a JQuery method that cancels the navigation behavior of the link and pops up a JQuery floating div to show the image on the current page. If the user's browser doesn't support JavaScript, the onclick event will never fire, and the user will be presented the image in a new page. The core functionality is the same with or without scripting.
EDIT: Skeleton example, sans JQuery-specific code.
<html>
<body>
Some URL
</body>
</html>
To cancel the navigation operation, simply make sure that the method invoked by the onclick event returns false at the end.
A neat example of the JQuery image popup I described can be found here.
Use ajax if it adds value for the user.
If the ajax version adds a lot more value than the non-ajax version then it might justify the expense to develop a solution that caters for both clients. Generally i wouldn't recommend doing the extra work (remember.. more code results in more maintenance).
I think one point is missing here: Use Ajax only for content any search engine does not need to know.
98% of users will have AJAX enabled browsers.
A significant percentage of those people won't have it turned on when they first visit your site though (or at all, ever perhaps).
I've seen websites that look like a blank page without javascript on. Don't be one of them. Javascript to fix layout issues is a horrible idea in my opinion. Make sure it loads and looks ok without Javascript. If people can atleast see what they are missing out on, they are likely to switch it on, but if your website looks like it's just broken, then...
I often have noscript block Flash and JavaScript until I make the decision that your site is worthy.
So be sure to tell me what I'm missing if I have JavaScript turned off.
It depends on the complexity of your web application.
If you can, having it functional with javascript disabled is great, because it makes your application usable not only by users on js-disabled browsers but also by robots. The day you decide to write an application to automatically fill your forms, for example, you don't have to write an API from the ground up.
In any case, do not user AJAX for EVERYTHING! I have just inherited a project that basically consists of a single page that is populated by a ton of AJAX calls and I can tell that you just thinking about it gives me physical pain. I guess the original developer didn't like the concept of using the back/forward button in the browser as a mean of navigation.
Unless you are targeting mobile devices or other non-standard web users, you can be fairly sure that the vast majority has Javascript enabled, because most major sites (including SO) rely heavily on it.
I want my application to be as accessible as possible.
You can do things like rendering your modals and forms as a page that can operate standalone.
The AJAX version pulls the template into a modal/container, the standalone version checks if it's an AJAX request and renders the page including the header/footer (this can occur from the same URL if planned well)
The AJAX version intercepts the submit and does AJAX submission then provides an inline thank you, the non-AJAX opens a thank you page. Once again you can likely use the same pages for each of these functions if thought out correctly.
Reusing templates and URL's helps avoid additional maintenance for the AJAX/non-AJAX versions.
I want my application to be enhanced by AJAX, but also fully
functional without AJAX.
Thinking through the structure of your URLs and templates can go a long way towards this, if you make most of your AJAX requests pull in completely rendered templates (as opposed to just data) then you can usually use the same URL to serve both versions. You just serve only the guts of the modal/form to the AJAX request and the entire page to a regular request.
When should I not use AJAX?
You should not use AJAX if doing so will cause a poor experience for a significant portion of your user base (there are of course techniques that can be used to mitigate this)
You should not use AJAX if the development time associated with implementing it will be too significant to justify the improvements in user experience
You should not use AJAX for content which has significant SEO value without implementing an appropriate fallback that allows it to be indexed (Crawlers are improving constantly but it's still a good idea)
I mean, should I bother making my application usable without AJAX? Or
does everyone have AJAX enabled browsers these days?
I'd say a lot of the time it's unnecessary as the vast majority of users will have AJAX enabled browsers, but there are scenarios where it's critical such as SEO optimization or when a large portion of your user base is likely to use browsers that are less likely to support Javascript as well or where they're likely to have Javascript/AJAX disabled.
A few examples of these scenarios:
A website for a company or government that uses an outdated browser as standard
A website where a large portion of the users may be disabled in a manner that may negatively impact their experience such as a website for vision or motor-skill impaired people may be negatively impacted by updating content via AJAX especially if it occurs rapidly.
A site accessed regularly via a less common device or browser that will cause a negative impact to a large portion of users
So what should I do?
Think about who is going to be using the site, how they're going to access it, and what they're going to access it with. Also try to think about not just the present but also the future.
Design the site in a manner that will cater to the majority of these users.
Think who will gain and who will loose based on my decision to use AJAX and if in doubt have a look at your analytics data to help weigh up the decision and if you lack the data it may be worth updating your tracking and obtaining a sample to aid the decision
Think does my decision to use AJAX cause any contradictions with core requirements for this project
Use AJAX to enhance content where possible as opposed to making it mandatory ie the content should work with or without JS/AJAX
Consider the additional development time involved with the use of AJAX (if any)
My experience is, we should use ajax after it works without it. For a couple of reasons.
First, if something breaks in the ajax, and you don't have it working without it, the site simply doesn't work. For example, a product list with pagination. It should work with the links alone, then use ajax when possible.
Second, for site indexing and accessibility. If it works without ajax, it's better.
And it's easier to break something (even if only for a few moments). A bad piece of code, an uncaught exception, an external library not loaded, a blocking browser extension,...
After everything works without ajax, its quite easier to add ajax. Just have the ajax catch the action, add ajax=1 and when returning the result, return only what you need if ajax=1, otherwise return everything.
In the product list example, I would only return the products and pagination html, and add to the correct div. If ajax stops working, the whole page is loaded and the customer sees the second page as it loads.
Ajax adds a lot of value to UX. If done right, the user gets a great feel when using the site, and better data usage because it doesn't load the whole page everytime.
But the question being "when not to use ajax", I would say, you should always count on it to improve UX but not rely on it for the site to work (as other users also mentioned). And nowadays we need both, great code and great user experience.
My practice is to use two main pages, let's say index.py and ajax.py. First one is responsible for generating full website, and is default target of forms. Other one generates only output specific for adequate ajax query. Logic behind both of them is the same, only the method of generating output is a bit different.
In jquery I simply change action parameter when sending a request. It works both with and without ajax, although long time have I not seen someone with disabled js and ajax.
I like the thought of coding your application without JavaScript / Ajax and then adding it in later to enhance the UI without depriving users of functionality just because they don't have JavaScript enabled. I read about this in Pro ASP.NET MVC but I think I've seen it elsewhere in reading about unobtrusive JavaScript.
You should not make your service bloated with web 2.0 effects like accordion, modal/etc forms, image zoomers etc.
Use modern tech smarter (AJAX is one of them) and your users will be happy. Do not fear AJAX -- this is very good thing to make user expirience smooth. But don't do things because you like it - do them because your user need it ;)
When you want to make a website that looks like a website, not a fugly imitation of a desktop app?
You should not use AJAX or JavaScript in cases where:
your system needs to be accessible
your system needs to be search friendly
However, by using a modern JS framework with some solid "unobtrusive" practices, you can progressively enhance pages so that they remain accessible and search-friendly while offering a slick UI to users.
This totally depends on the type of application or feature you're developing. If it is crucial that the application is accessible despite the absence of Javascript, then it would help to have fallback methods (i.e. alternative forms) to allow your user to use said functionality/feature. For that, it will require you to invest some of your time developing methods for collecting information not just using client-side scripts but also on the server-side.
For miscellaneous features that only serves to enhance user experience, it's mostly not worth it to develop fallback methods.
There's no reason to totally not use AJAX. AJAX helps minimize your traffic after all.
You can if you wish always use AJAX and update the history state using Push State or for more compatibility use the hash with none HTML5 compliant browsers.
with this you can have your server load a page then javascript read the document.hash and resume the state of the application base on the state of the hash.
for example i got to /index.html i click into something for example a client to open the view client you can change the hash to #/view/client/{client_id}/ then if a reload or go back using the browser the hash with change and you can use the onhashchanged event to capture it and match the sites state to the new hash then same if a favorite a certain state
A couple of other scenarios where one may be better off NOT using AJAX:
Letting someone to log into the web application. Use traditional form submit instead.
Searching and returning more than a few 100 rows from the database. Either break the process down or let the server side language handle it.