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I’m planning on using Ajax with my web application, but as I’m novice and don’t have much experience I wonder when ajax should and when should not be used? I plan to code with jQuery/php if it makes any difference.
AJAX is most useful when your application wants to present a data set to its user in many different ways. Sorting and filtering and in general interacting with a data set feels best when there are no delays waiting for a server to redraw the pages and send them over the network. It's also nice for handling display of new data arriving on the server -- the client can just pull the data that is new and merge it into the data set on the client rather than requiring a whole new page draw including all the data you've seen before. This can save quite a bit of bandwidth.
AJAX should not be used when you need to keep your application simple, though technologies like jquery are making the client side easier and easier to get right. But in general I would say that if the information you're delivering is pretty static -- it only needs to be viewed in one or two ways, then an AJAX approach may just be overengineering.
That is not an easy question to answer without more information about your application. I find myself using Ajax to save very complicated pages. For instance I might have a page with a datagrid on it where people can enter multiple records at a time. It is also nice when you want to do partial updates of pages maybe when filtering a list or doing paging. Using ajax usually a lot more work than just posting back to the server so don't go too overboard.
For me, Ajax is useful in interacting with the DB, and for JQuery is for trapping entries of the user without bothering the whole page. So AJAX and JQuery, if mastered, will create a one hell of a website.
For when not to use it see When NOT to use AJAX in web application development?
In terms of when to use it my thoughts are:
When you don't want the user to endure a full refresh of the page when they trigger an action
When a rich UI is important to you.
When you can achieve the same effect without using AJAX using Jquery/JavaScript
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I have zero web programming experience but has been in IT industry for a while, mainly as a CRM technical consultant. I'm familiar with VBScript and Javascript, not in a Web context but as general scripting tools. I'm good at designing business processes, database models and using DB queries. I have some basic understanding of GAE and Python by doing the tutorials by Google. I used to write some tools with C# and VB6 a long time ago.
So I've decided to build my first website on Google AppEngine, and I'm lost in so many choices and new skills to learn.
What I'm planning to build is a simple website where users can post short messages and vote upon them. Which requires a simple but dynamic front page, login/cookie handling, Reddit like post voting/aging and some data storage.
Maybe the first question is which framework should I use? I heard Flask is good for beginner to learn web programming and webapp2 is easy to start since it's integrated to GAE by default. I've looked at Django as well, it looks very powerful, but I couldn't decide.
Since my idea is largely based on a concise but dynamic front page, I guess something AJAX is a must. But I have no clue on where to start. All those Ajax, Jquery, ProtoRPC are so confusing. Which technologies should I use and where can I find good tutorials?
I am also looking for suggestions on potential challenges and anything I should learn to achieve my goal. Thanks!
Since your project is inspired by reddit, the web development course with Steve Huffman (the technical founder of reddit) will be extremely helpful for you.
https://www.udacity.com/course/cs253 - it's free if you just watch the courseware. He even explains their aging algorithms in the end.
This course covers the back-end side of building a python applicaiton with the default webapp2 framework on appengine. He doesn't cover the front-end besides the basics (HTML forms and tables, stuff like this).
Now, Jquery is a Javascript library which is used by about all of the dynamic websites. It is a convenient way to work with the DOM on the fly. Everything you can do with jQuery, you can do with plain javascript, it's just that jQuery is infinitely easier to work with.
This library is used on the front-end, and it doesn't matter what backend you choose. It is extremely simple and powerful and you can learn the basics at the free codeschool course try.jquery.com.
Basically, if you want something to happen on the page dynamically (the arrow becomes red once the user clicked on it), you use jQuery.
AJAX is asynchronous communication with the server, it can be done by plain javascript but jQuery provides a very convenient wrapper for doing it. Usecase: the user clicked on the arrow, you painted it in red with jQuery, you incremented the votes counter (again with jQuery), and now you need to send the upvote to the server without reloading the page. For this you perform jQuery.ajax() call, and pass the user data as a param.
So to wrap it up: you need to write javascript to make a dynamic page and jQuery is the most common library that helps you with this. You need AJAX to get and post data to the server without page refreshes, this is implemented in jQuery. You can use jQuery with any back-end framework that you choose. Start with the simple jQuery tutorial, then read about $.ajax call and it will be clear for you.
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Single Page Apps are well known. But PageAx seems to be less well known. I stumbled across it by accident in learning MVC and it has worked quite well for me so far.
(Note: I am aware that this is a topic which may be regarded as "not answerable" and "should be closed" yet I feel this is an important topic which has not yet been covered. Note that this is Single Page Apps vs. PageAx (not Ajax). I am looking for benefits/disadvantage type discussion. I am making up the name "PageAx" as I have not found a better term for it.)
SPA - communication with controller via Ajax and returning Json.
PageAx - communication with controller via Ajax and returning partial views which replace divisions.
Here are the benefits of PageAx as I see it, over SPA's:
Little to no JavaScript on the client.
I find Partial Views very easy to write on the server side.
Benefits of SPA over PageAx:
I can't think of any.
Disadvantages of PageAx over SPA:
Slightly larger payload (but I doubt it would be discernible by end user.)
I can't think of any other.
Disadvantages of SPA over PageAx:
Seems like the amount of JavaScript and required libraries present a fairly large learning curve (i.e., more so than MVC.)
So to re-iterate the question, are there any advantages to SPA over PageAx? The basic reason for the question is that I am starting yet another web project and need to decide which way to take it.
This depends on complexity of your application.
Returning JSON is beneficial because hey—that means you have a full-fledged API that you can reuse in a mobile app or a desktop client. Even if you later decide to completely re-do your frontend, you will already have a ready-to-use backend to code against.
Also, if your webapp is highly dynamic and interactive, replacing partial views may not be enough. You may want to have finer control over transitions (e.g. animating them). For example, see Medium-Style Page Transitions: you can't do something like this with partial AJAX views.
On the other hand, if this flexibility doesn't buy you anything, rendering partial views on the server may work very well for you. Here's David from 37signals blogging about it. He calls this approach SJR (Server-generated JavaScript Responses):
This doesn’t mean that there’s no place for generating JSON on the server and views on the client. We do that for the minority case where UI fidelity is very high and lots of view state is maintained, like our calendar. When that route is called for, we use Sam’s excellent Eco template system (think ERB for CoffeeScript).
If your web application is all high-fidelity UI, it’s completely legit to go this route all the way. You’re paying a high price to buy yourself something fancy. No sweat. But if your application is more like Basecamp or Github or the majority of applications on the web that are proud of their document-based roots, then you really should embrace SJR with open arms.
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I know what AJAX stands for. I know javascript passably well. But frankly I'm just not clear on what AJAX is.
Because all I know about it is XMLHttpRequest(), but it must be so much more than that. Can someone give a clearer explanation of how AJAX isn't just a certain aspect of perfectly ordinary JavaScript? I can't see how it's anything different.
EDIT: I also understand that it allows you to update a page without reloading. That's fantastic, I know. But I still don't see how that's anything more than standard JavaScript.
Well it's not as if it's magic or something. It really is ordinary Javascript, and it's ordinary XML (or JSON, or some other data format). And it runs in a browser. None of this is particularly new or novel. Microsoft was talking about "DHTML" in 1996, and officially released it in 1997.
But combining these existing things, is an approach that is common enough and useful enough to have earned a specific name. AJAX refers to
the pattern of using asynchronous requests, driven in Javascript logic running in the browser, to retrieve data in XML format or otherwise. Typically the retrieved data is then used to update the HTML page in some way, without causing a full page refresh.
You said you don't see how that's anything more than standard JavaScript.
Using Javascript in a browser you could do something as simple as run a timer that pops up an alert after it expires. Or you could perform a fadeout on a background color. Or do jQuery effects like accordion popouts. Or dynamically sort an HTML table by different columns. Even autocomplete in textboxes is possible using Javascript. These all cause the UI to be updated, but they don't necessarily retrieve any data. (in some cases autocomplete will do so, but not generally).
AJAX always involves communication and data retrieval, so it is distinct from "standard Javascript".
I think to gain an understanding you have to look into where the XMLHttpRequest came from. It was not a standard part of JavaScript at the time. You could not make asynchronous HTTP requests from the browser with pure JavaScript. The XMLHttpRequest object was first introduced by Microsoft in IE5 as an ActiveX control. So with that in mind, the way we use JavaScript today has evolved from a much simpler scenario.
I suggest you read the Wikipedia page - particularly the history section. There's nothing overtly fabulous about Ajax, it was just a coined term for what was at the time a new way of doing things, and it's stuck.
http://en.wikipedia.org/wiki/AJAX
In particular read the definitive article http://www.adaptivepath.com/ideas/ajax-new-approach-web-applications - this is probably the best way to understand where Ajax came from and indeed what it actually means. Probably most importantly
Defining Ajax
Ajax isn’t a technology. It’s really several technologies, each
flourishing in its own right, coming together in powerful new ways.
Ajax incorporates:
standards-based presentation using XHTML and CSS;
dynamic display and interaction using the Document Object Model;
data interchange and manipulation using XML and XSLT;
asynchronous data retrieval using XMLHttpRequest;
and JavaScript binding everything together.
As noted, the exact definition of Ajax is quite hard to pinpoint these days. The methodologies are prone to updating themselves as the browser evolves, but these were the underlying principles at its conception.
"Asynchronous Javascript and XML" -- you're right, it's really just a component of Javascript. From the server side, it's literally nothing: the server doesn't know or care whether it's fielding an AJAX request or a "normal" request (although of course the web application would know and care). It just happens to be famous and have a fancy acronym, because it's very useful in designing web sites.
EDIT: definition from the W3 spec http://www.w3.org/TR/XMLHttpRequest/:
The XMLHttpRequest specification defines an API that provides scripted client functionality for transferring data between a client and a server.
JavaScript happens on the client-side. Ajax uses javascript to receive a REMOTE response from the server without loading the page.
It's a way of getting and sending data from and to the server asynchronously without refreshing the page. Data exchanged used to be just XML (the "X" in AJAX), can now be other things (e.g. JSON or even JSONP).
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So I actually saw a full ajax site somewhere (I forget where) and thought it would be something new and fun to try. I used an old site I had built and put it on a new server. With a little bit of jquery and ajax, I was able to make the entire site work on one page load.
My question is, what are some pros and (more likely) cons to this method?
Please note - the site works through a semi clever linking function. Everything works perfectly fine if the user doesn't have javascript enabled, the newly requested page loads like it would on any other website.
More detail -- Say the user loads the homepage of the site, then logs in. When they log in, the login box fades and reappears with user info. Other content on the page loads as necessary upon logging in. If they click a link, lets say "Articles", one column on the homepage slides up and slides back down with the articles. If they click home the articles slide up and the homepage content slides back down. Things like posting comments, viewing profiles, voting on things, etc. are all done through ajax.
Is this a bad method of web design? If so, why?
I am open to all answers/opinions.
IMO, this isn't "bad" or "good". That depends completely on whether or not the website fulfills the requirements. Oftentimes, developers working on AJAX-only sites tend to miss the whole negative SEO impact issue. However, if the site is developed to support progressive enhancement (or graceful degradation depending on your point of view), which it sounds like you have, then you're good. Only things to prepare for are times when the AJAX call can't complete as expected (make sure you're dealing with timeouts, broken links, etc) so the user doesn't get stuck staring at a loading icon. (The kind of stuff you'd have to deal with in any application, really.)
There are plenty of single-page websites out there using heavy JS and AJAX for the UI and they are great. Specifically, I know of portfolio sites for web designers and web app development teams that use this approach. Oftentimes, the app feels a bit like a flash app, but without the need for a special plugin.
"Is this a bad method of web design? If so, why?"
Certainly not. In fact, making web-pages behave more like desktop applications, whilst remaining functional to ALL users, is the holy-grail of web-design.
I say, as long as you consider ALL your users, i.e. mobile/text-only/low bandwidth/small screensizes then you will be fine. Too many developers just do it for their huge 19" screens and 10Mbps, that users to get left behind through almost no fault of their own.
It depends on the user
This relates closely to UX, IMHO, though of course it's on-topic for programming solutions.
All-AJAX is often called "managing state" 12 years after this Question was asked.
From my experience in:
Creating a platform for API plugins
Creating two of my own CMS web apps for different purposes
Managing many different WordPress.org sites for different purposes
Managing my own cloud servers for both PHP-AJAX and Node.js doing these calls
...it depends on what is most efficient for users.
Consider these scenarios:
Will users be clicking around this website all day long or for at least an hour adjusting many different options and <form> inputs?
Or will many users visit briefly to perform just a handful of quick tasks?
State-managed / all-AJAX is by far best for scenario 1, with Facebook and Gmail as prime examples.
Whole-page loads are more efficient for scenario 2, like blogs, especially with pages linked directly from search results. That might apply to webstores like Amazon, maybe, where users search Google to find one or two products, then leave.
Philosophically, I've heard that the difference is about the number of users and traffic, but I don't quite agree. It's more about how much clicking and <form> sending the primary target user will be doing.
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Closed 12 years ago.
My friend and I are building a website together, and he is insistent that page refreshes are a thing of the past and that we should build the whole website in AJAX. His only reason why page refreshes are 'annoying' is that they are too slow.
However, the page is running fine without AJAX currently and when I click from page to page, it seems instantaneous to me. It doesn't seem that it would benefit from additional speed, but he just says I'm being stubborn.
I do want to use AJAX for certain features and pages within the site. I feel like I understand the pros and cons. He references that gmail is made in AJAX, but the url changes as I go into different mailboxes, so I don't think it is 100% AJAX.
I reference wikipedia, which is actually much more similar to our site, as an example of a highly succesful website which doesn't seem to NEED AJAX. But he says that's just one example, and that I am fixated on on wikipedia.
Some personal rant:
1. When I tell him that AJAX is great, but that most of the internet will still require page refreshes and page links, he thinks I'm crazy.
2. When I tell him that using AJAX when not needed will make the back-button useless, he tells me that I'm obsessed with the back button.
3. I think AJAX is something that can be added later to make functionality smoother on certain features, but that it is OK to build the core of the website without it for now.
What is your opinion on the matter? When is ajax really needed in a website?
Thanks
No, Ajax is not necessary for a website to be great. But it can improve usability if used correctly and not overused.
A site built entirely with Ajax and non-functional with JavaScript disabled is a nightmare. No navigation back/forward. No bookmarking. Not to mention its effects for SEO, that is the site will be invisible to search engines.
The golden rule: build the site in classic fashion then add little elements of Ajax to improve usability now and then.
For certain advanced functions it might be okay to be only available as Ajax, but try to make sure the most of the site is at least accessible in read mode when JavaScript is disabled. StackOverflow is a great example of that approach.
My rule of thumb is - what are you building: a website or a web application?
if its a website, content should just NOT be loaded via ajax. It breaks many assumptions that the end users have about the website. Other problems:
1. SEO
2. back button breaks
3. more work to do on your side to make the website UI consistent
4. placing relevant ads will be more complicated
An excellent example is wikipedia.
If its a webapp, then ajax can really help:
1. you can design better user interaction
2. the user will actually expect the app to behave like a rich app, and not like a website.
3. you can dramatically increase the responsiveness of the app using ajax.
I hope that helps.
Of course, AJAX is not necessary to build a great website. It can, however, improve the user experience in certain situations. It is necessary to carefully study and understand your requirements, the structure of your site, and the navigation your users will undertake.
One important thing to consider, however, is bookmarks. Using AJAX extensively makes it extremely difficult to be able to simply bookmark a certain spot or "state" of your website.
Sorry to not post on topic, but I agree with the answers other posted (AJAX in great if not used too much.) It also DEPENDS on the website, if it's more like a web app where you don't need SEO and bookmarks (like gmail) you can go with full ajax (try GWT), if it's content rich- go with just a little AJAX.
But what I wanted to underline is the relation with your friend: you have to be careful when you start a big website with somebody else. If your fight is too big for such a detail you'll have much more problems later.
Get a website that supports a lot of connections, see how they do things and you might understand where and when ajax is used. Start looking at StackOverflow for instance.
This entire site is serving 16 million
pages a month and we are doing it off
of 2 servers, which are almost
completely unloaded. The Microsoft
stack is a pretty good stack.
Joel Spolsky, StackOverflow.com
Form validation using Ajax is the way to go.
I hate clicking "Submit" only to have the page return in a few seconds saying my password is not strong enough or that user ID is already in use. It should be instantaneous while I'm filling in the fields!
As far as StackOverflow, I think it's great how when I click on "Show additional comments", I see the spinner and then they immediately appear. When I change the sort on the answers by "newest" say, I hate how the page refreshes.
I don't think you need Ajax for a site to be great. That said, more sites that are great make use of Ajax. Good RIAs are awesome.
I dont see a lot of ajax on Digg, ArsTechnica, LifeHacker, and the such. Those are all (subjectively) pretty good sites.
No, you don't need it. It just needs to perform well for what your intended audience needs.
Yeah I think you do need it, having to submit pages is so pre-millenium.
More seriously, if you are presenting data, I really think it improves the user experience if asynchronous calls to server are used and the returned data displayed without the need for a complete page refresh.
I remember the first time I saw it used (years back) I was extremely impressed, awed even.
Anyone got example of dynamic, data driven websites that look great and don't use ajax ?
AJAX is not an absolute NEED for a website application. It does not necessary mean that your page will be faster. A lot more things determine page speed, such as:
client side minifying (css and js)
image compression and sprites
server location
and much, much more
Of course, applying AJAX in some strategic point of your website will be where you will most benefit from it. Use it where there is likely to be a lot of activity from your users. I personally always make my website without any http requests handling at first, and then implement the rest by adding AJAX where there is the much concern.
I think your friend is being a bit too concerned about AJAX. Like everything in life, it always tastes better with moderation.
One potential downside of AJAX, when misused, is that content can't be bookmarked.
Try and follow the rule of thumb, that the user should be able to link to content by copying the URL from the address bar. There are several ways to achieve this, with traditional page loads being one.
AJAX is not a must for any website. But if your website has voting, save as favorite, or add to cart, etc ajax will definitely add value.