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What makes Angular and Backbone different from jQuery?

I have been using JavaScript and jQuery for quite a while now and want to extend my skill set further, during my search I came across two popular names Angular and Backbone and while reading about them I found one line common in both them which somehow also seems to be their USP i.e.
It is designed for developing single-page web applications
This makes my confused.
What is that I cannot do with JS or jQuery and I would require these?
I have created web application on single page, where users can perform CRUD operations on single page through asynchronous calls so why so much importance of for these others libraries?
And as a middle level web developer who has have good hands on JS is it right path to move to these two or here is something else I should look into before these?
Please help?

Structure.
In an ongoing project that started about 4 years ago we built the front end with jQuery. We were able to do just about everything that we needed creating several single page applications that were quite functional.
As the project progressed and the code base grew we started experiencing some major problems with maintainability of the code. We ended up with hundreds or thousands of lines of JavaScript code per page in a tangle that was almost impossible to navigate. This could have been avoided if we were more careful of course but at the time we focused on making sure the back end architecture was robust.
Many years ago the community learned that code needs structure to be maintainable. We developed MVC patterns, multi-tiered applications etc. But JavaScript was never a big player in the field and we largely ignored it.
Over the last 6 months or so we introduced Angular into the project and started sorting out some of the mess in the project. The results are remarkable. Not only is the code simpler and easier to create, the structure makes it easier to implement tests, easier to maintain and generally a huge improvement over what we had before. We still use jQuery but now we have been burnt by the lack of structure and know a thing or two about the architecture of a JavaScript application. Angular and its like provide you with the tools to architect a good application.

When you are creating larger scale web applications it is wise to check out Backbone, Angular or perhaps Meteor. jQuery supports neat tricks, but it does not help you structure your code in a maintainable way. Larger scale web apps build on jQuery need their own vision on how to separate the code into layers with their own responsibility.
The other frameworks give more support.
I would suggest checking out at least one of the libraries. Perhaps you eventually won't use them, but it will benefit how you work in jQuery.

Well Now a days there has been quite a hype about Angular.js and especially SPAs (Single Page Applications). Well to be honest, I had the same question in my mind about a month ago when my team decided to shift from Jquery to Angular.
Whenever it comes to Jquery, one of the first thing that comes in our mind is the DOM manipulation. While using Jquery we always think of manipulating the DOM. Show/hide elements, animating elements, getting data from tags you name it. But Angular offers something more than that. It offers you an architecture, a way to structure your applications at the front end.
So whenever you go for Angular.js, change the way you think about creating web applications (and believe me its worth it). Most of Angular's structure uses the concept of Dependency Injection which is a neat way to maintain your code.
Backbone is only a library whereas Angular.js is a complete framework to create and manage Single Page Applications
Talking about the fact that Angular.js should be used when we are creating large scalable apps, it is true. In my case the team I work with is full of Jquery Ninjas. We have been creating a great app for the last 3 years and believe me it became difficult for us to maintain and debug thousands of lines of Jquery. This is the main reason we have decided to revamp this app into Angular.
Kindly see some of these Helpful links. You will get a better idea.
http://net.tutsplus.com/tutorials/javascript-ajax/3-reasons-to-choose-angularjs-for-your-next-project/
"Thinking in AngularJS" if I have a jQuery background?

Need help determining how to approach building my project

I'd like to create something similar to a family tree online app (like geni.com). I'm unsure what languages I should use to build it with. My IT strong points aren't in programming and this project is going to require me to sit down and learn some languages. My problem right now is that I don't know what languages I should use.
So with the idea of a family tree online app in mind here are some of the specifications.
- I do not want to use flash.
- The app needs to be zoomable and scrollable (sort of like google maps)
- The app needs to be able to add content without reloading the page. Perhaps there's a little "+" sign and when I click it, I can add a tag/title/description/picture
- The app needs to be able to save your work for that user to retrieve later on.
- The layout that a user is able to create in is sort of widget based where the user can add a new bubble and then in that bubble they are able to add text or content.
I started programming this with HTML5 canvas and Javascript, but I'm stuck on creating a connection to the database that isn't directly from Javascript (because that seems very insecure to me). But I'm not just stumped on how to interact securely with the database (I don't even have a database picked out), but also I'm concerned that I won't be able to build out the app with just javascript and may need something else like ajax or something but I'm unfamiliar with what each language does nowadays.

If you are starting from scratch, then the best language to use is the one you are most comfortable with. Alternately, if you don't plan to be developing the whole thing yourself and you already have some other interested parties on board then the best language to use is the one that the majority of you are comfortable with. If it's just you and you do not yet have any favorites, then look around and play with a few - it's the only way to find out if you will actually like / be effective with them.
That being said, a few of the more likely candidates these days are:
JavaScript: Long gone are the days when this language was simply a way to put the D in DHTML. These days JavaScript is a viable client and server-side language. (Others here have already recommended Node.js -- I'd also recommend NPM (node package manager) to handle your dependencies). With a little bit of planning you can reuse most of your application code on both the client and the server side. On the downside, most of the server side technology is very new (only a few years old at most) and so you may find yourself implementing tools for use in your application rather than your application itself. Finding servers that support it will also be harder, again on account of it's age.
Perl: At the opposite end of the spectrum of age, we find Perl - the first commonly deployed language used to make web applications it still powers a great variety of useful websites out there (include new ones such as Pinboard.) The tools that are popular on CPAN have been vetted under fire. The good news is that it is not going anywhere anytime soon. The bad news is, you might have to search a little harder to find a module that supports [that newest, baddest thing that just came out yesterday].
PHP: The BASIC (or Perl, depending on who you ask) of the modern web, PHP was designed from the ground up to do one thing - make building dynamic web pages easier. Its popularity means that there is quite a lot of server support (PHP + Apache + MySQL is the Model T Ford of web servers -- everyone can afford one) and an enormous amount of pre-built code available for perusal. However, like BASIC, PHP's strength is also its greatest weakness. Almost anyone can write something that works in PHP ... how well it works depends on who wrote it. The caveat emptor that applies to all code snippets found on the web applies in spades to snippets of code written in PHP.
Python: The language that made programing fun again (at least for those who can see past the significant whitespace and lack of blocks / anonymous functions and overlook < 3.x's issues with non-ASCII out of the box.) It's a general-purpose, flexible and multi-paradigm language with quite a substantial standard library (but without .NET or Java's incredible bloat). In addition, quite a large amount of work has been done in it, so there is a good chance that what you need has been already developed by somebody else. Plus, it can make you fly.
Ruby (with or without Rails): The language that made the web fun, coupled, if you so desire, with the framework that made MVC cool. There is lots of documentation out there, and a great community, with many prebuilt tools (called gems) from which to pick and choose - free and cheap servers are not as common as their PHP counterparts, but they are likely to be of higher quality (when chosen at random).
All that being said, they are all great languages for web development. What matters is not what we think you should use ... but what you are most likely to be effective with. All of the languages listed above are mainstream (or will be in the next two years), easy-to-learn and easy-to-write languages. You cannot go wrong, no matter what you choose to start off with.
Alternately, if you want something a little more difficult, or less mainstream ... I am working with .NET applications at work, and with Lisp (SBCL)-based services in my spare time. I have heard great things about Lua and Java too ... there are at least two C++ web frameworks out there ... and I'm sure that there is somebody is having fun building a web service in COBOL with a FORTRAN backend. ;-)

As someone has already pointed out, you will need to work with a server side language as well. (Ruby, Python, PHP) You are exactly right there you should not be attempting a database connection via javascript in the browser.
You'll need to build out a server side application to handle the basic operations of your application.
I'd strongly recommend reading up on the MVC design pattern, and possibly looking into Ruby on Rails as your backend framework, it plays very nicely with ajax like features, and has a somewhat shorter learning curve, I believe, than some other frameworks / languages.

You will need server side scripts in a language like PHP or Ruby on Rails to interact with a database.

If you're already familiar with HTML5 and JavaScript, may I recommend using Node.JS? It's about the closest you'll get to what you already know with browser development. It can also hook in with database systems which are closer to the HTML5-suggested IndexedDB.
with that in mind...
If you're inexperienced with programming and programming languages, then the app you describe will involve a pretty big learning curve. While Flash and Flex have really nice interfaces to build apps with click-and-drag, the tools for HTML5 are much less mature.
That's not saying it's not possible with HTML5. Just that there's still some time to wait before people create tools to bring the app building process closer to what Adobe provides.

What JavaScript UI testing framework should I use for a simple HTML5 + jQuery app?

I'm about to write a simple HTML5 + JavaScript (jQuery) app in my spare time in order to keep up with the latest web technologies (at work it's more advanced C# backend stuff).
I'd like to develop in the same fashion that I've done for the last ten years or so, namely TDD style.
Being new to the TDD/BDD/AcceptanceTDD world in HTML/JavaScript, my question is: is there a great framework or the like for writing test against a web page in a browser (out-of-the-box support for many browsers being a definitive plus)?
The reason I'd like to use JavaScript is two-fold. 1. I'd like to learn more JavaScript, and 2. I'd like to use the same language(s) for the tests as I do for development.
Otherwise, I could simply use my C# skills and use Selenium, WatiN, or a similar framework.
I've found Jasmine, QUnit, and a homegrown solution using jQuery at MSDN, but don't get a feel for the flow nor complexity, so recommendations and first hand experiences are more than welcome.

JS Test Driver is the framework recommended by the Javascript TDD book from O'Reilly that I'm reading right now. I haven't actually had a chance to play with it much yet, but:
A dude who wrote a book on JS testing recommends it
It has a very nice feature set (automated test running across multiple browsers being key)
It comes from Google (love 'em or hate 'em, they have a lot of smart JS people working there)
So at the very least it's worth checking out I think.

At this point, I'd recommend Jasmine. I've used it successfully on a few projects. I haven't really run up against too many frustrating situations where I just couldn't get something done (unlike other tools). It can be set up in different configurations, depending on your preference-- it can be as simple as opening a page in a browser, or it can be "served" dynamically.
There are dozens of tools out there in general usage-- and so far-- no clear winner. I've tried a quite a few of them, and-- as John Resig points out-- creating a simple testing framework isn't that complicated. But adding some tools to make it convenient is important. Jasmine is the most complete one I've used, but it's not bloated.
Important considerations:
set up: don't adopt a tool that doesn't work easily out of the box
style: use a tool that makes sense to you in the context of the rest of your testing tools. For example, if you use BDD tools, find a BDD Javascript framework. This is probably the biggest variance in the frameworks-- might as well pick one that has a syntax you like.
cross-browser: the tests should work across browsers
automation: you should be able to script the running of the tests in one or multiple browsers
testing time-based code-- if you Javascript has behavior tied to the clock (as in animations), having a testing framework the facilitates this is nice
mocking: jasmine has a nice mocking support that really helps
You really do not need to use Selenium for simple unit tests-- it complicates the configuration and is a more difficult programming model than a simple unit testing framework.

I've struggled with this a lot. I think Selenium is your best bet especially since it sounds like you've used it before. The other stuff for JS is mostly unit testing.
Not to diminish machineghost's answer, JS Test Driver rocks for unit testing.

I ended up using QUnit since I found it very simple to just insert the PUT (Page Under Test) in an <iframe>, and use jQuery to access it from the unit tests.
That way I don't need any other external dependencies other than the browser itself (the logic resides 100% in the client) and any text editor.

Turboframework uses javascript, jasmine, selenium and runs with node. You can literally create a test project and run web automated tests in less than 10 minutes. To avoid repeating the documentation that is already available, here's the link to a quick start guide:
https://turboframework.org/en/blog/2021-03-03/automate-your-web-application-tests-in-less-than-ten-minutes

Pure JavaScript-based clients

I would like to know, how powerful/viable are JavaScript only clients based on say, GWT/gxt/vaadin, when compared to DHTML clients such as those made with wicket, tapestry, click etc?
My boss has insisted on using GXT (due to its nice colors and theme) on a project that will most likely become very big with lots of screens. I am against the idea of a javascript only client, especially when the javascript is generated from Java code. I have tried to advice him that we use something like wicket whereby we construct the screens with html but put in ajax where and when neccessary.
How viable is such a JavaScript client? I understand that JavaScript was intended for minor web page enhancements, and not all browsers, especially mobile devices have complete support for JavaScript.

Yes, it is viable for certain applications. Consider Gmail, Google Docs and Google Maps as typical applications where this works, and is probably the most feasible approach.
Some rich UI JavaScript frameworks, such as Ext JS also rely on this technique.

I've built javascript only web apps for ages.
First in SAP projects for big multinationals. And now on a new project:https://beebole-apps.com?demo
So yes it is powerful and viable.

Javascript-only webapp can be extremely powerful, and it's viable for certain applications, say, an Instant-Messenger webapp?
You mentioned that there are lots of screens in your web-app. One of the advantages from GWT/GXT is the fact that you can unit test your UI-layer with JUnit. This is an extra testing you can do on top of, say, Selenium. This is essential if you'd like to make UI testing a part of the continuous integration process, and, as the team grows, you'll definitely want to have tests around to make sure everything works (At least in theory.)
However, if what your boss meant to do is to build an in-house, custom Javascript engine using GWT's JavaScript Native Interface (Link), then I'm not sure...
Another advantage with GWT-like-engine over Wicket is that you can rely on HTML-code-gen to generate standard-compliant (In theory) HTML code. With framework like Wicket, it is hard to ensure every single developer on the team to author good HTML code - Especially when the team gets bigger.

Disclaimer: I'm a member of the Vaadin team.
Our Timeline demo is a good example of what can be achieved with Vaadin and GWT in client side, but I think all of the options presented in this discussions are viable given enough time.
Since you are going to start a big project you should build a simple proof-of-concept app with each of the relevant frameworks. If your PoC includes at least some of the more complex use cases you'll probably can make a pretty informed choice based on the experiences you get while building them.
I urge you to at least evaluate Vaadin. With it you write only server-side Java code and Vaadin will create a slick and professional browser UI for you. Client side can be easily extended using standard GWT (also pure Java), and there are no HTML templates, tag libraries or XML configuration involved at all. A Vaadin UI is fully Ajax'ed and lazy loading out of the box, and it easily integrates with any server side technologies, eg. Spring.
In addition to the development model advantages you get top-notch documentation, a bi-weekly update schedule, a very lively community filled with helpful experts, 100+ useful open source add-ons, and a 10 year old backing company with help on hand should you need it.

Should I use Google Web Toolkit for my new webapp?

I would like to create a database backed interactive AJAX webapp which has a custom (specific kind of events, editing) calendaring system. This would involve quite a lot of JavaScript and AJAX, and I thought about Google Web Toolkit for the interface and Ruby on Rails for server side.
Is Google Web Toolkit reliable and good? What hidden risks might be if I choose Google Web Toolkit? Can one easily combine it with Ruby on Rails on server side? Or should I try to use directly a JavaScript library like jQuery?
I have no experience in web development except some HTML, but I am an experienced programmer (c++, java, c#), and I would like to use only free tools for this project.

RoR is actually one of the things the GWT is made to work well with, as long as you're using REST properly. It's in the Google Web Toolkit Applications book, and you can see a demo from the book using this kind of idea here. That's not to say that you won't have any problems, but I think the support is definitely out there for it.
There's a neat project for making RoR/GWT easy that you can find here (MIT license). I haven't had a chance to try it out yet, but it looks like a good amount of thought has been put into it. One catch is that it looks like it hasn't been fully tested with 2.1 Rails yet, just 2.0, so you may run into a few (probably minor and fixable) errors.

If you are looking to integrate GWT with non-Java backends such as ROR, PHP etc., you should bear in mind that GWT 1.5 now supports JavaScript Overlay types. This feature lets you write classes that can be mapped over the top of native JavaScript objects to easily provide accessor methods for properties of those objects and other extended functionality.
See this link for more details:
JavaScript Overlay Types
So you could return JSON encoded data from your backend via AJAX calls, parse it into a JavaScript Object and then access the data through your GWT Java code using the overlay classes you've created. Or when you render your page you can render static config data as JavaScript Objects and read it in via this mechanism, rather than having to do an AJAX call to grab the data.

If you know JAVA, and have somewhere you can host it (like a tomcat or glassfish container) I would recommend that much more than using Ruby for the back end. The main reason is that then you can share all of your objects, and use the built in RPC mechanism. I've done this for quite a lot of our projects and it's a huge timesaver, not to mention that the code is less error prone, because you don't convert your java objects to anything and then back again.
I have linked my GWT with Rails before, using the to_json function in Rails and then reading the JSON in GWT. It's all supported, but it is far more annoying than just doing the back end in JAVA.
Of course if you have cheap hosting, then Java containers are pretty much out of the question, in which case I would think Rails would be the next best thing.

GWT is very high quality with a great community. However you do need to know CSS if you want to adjust the look of things (you will) - CSS can do a lot of the layout, just like regular web if you want it to. Libraries like GWT-ext or ExtGWT can help a bit as they have stunning "out of the box" looks but for a price (extra size to your app).

You can code everything in Java using GWT, and you can integrate existing 3rd party javascript libraries with it. It's very good. I've never used RoR much though, so can't say anything about that.

If you're experienced in Java but not in Javascript/CSS, then GWT is going to be a lifesaver (unless you want to learn them, of course). CSS has so many little fiddly details. It is not uncommon to spend half a day fixing a 2 pixel misalignment that only occurs in IE6.
I am not sure about how easy it would be to use ROR for the back end... It is possible, I am sure, since GWT ajax communication is just servlets. But they provide some really nice functionality for passing Java objects back and forth which you won't be able to utilize if your server isn't also using Java.

I wrote about some of the disadvantages of GWT recently. Mainly, the disadvantages are: long deployment cycle for changes to some parts of the application and a rather steep learning curve. As a seasoned Java programmer, the second should be less of a problem and if you use a seperate backend, the first is also mitigated (as a complete redeploy is primarily required when you change the 'server' part of the application).

GWT is a wonderful framework with lots of potential. Keep in mind that it's still quite new, though. There are some unresolved bugs that can really annoy you, and they usually require ugly workarounds to get past. The community is great but you'll probably end up with a few problems sooner or later that Google can't answer yet.
But hey, I say go for it. The potential for GWT is awesome, and I bet it's future will be bright.

You should definitely use GWT for a new project (it's pretty easy to use in an old project too).
I my experience it's very fast to learn and use. The compiled javascript code is much better than anything you could ever write by hand and it works fast too.
Another benefit is the ability to debug you're code (which is hell with javascript alone)

This blog has inputs from many experienced users of GWT and have some great discussion points. I personally have huge experience with varied UI Frameworks. I will add my two cents. Lets look at fundamental advantages and disadvantages of GWT
Fundamental Advantage
GWT takes the web layer programming to JAVA. So, the obvious advantages of Java start getting into play. It will provide Object Oriented programming. It will also provide great debugging and compile time checks. Since it generates HTML and Javascript, it will also have ability to hide some complexity within its generator.
Fundamental Disadvantage
The disadvantage starts from the same statement. GWT takes the web layer programming to JAVA. If you know JAVA, probably you will never look out for an alternative language to write your business logic. It's self sufficient and great. But when it comes to writing configurations for a JAVA application. We use property files, database, XML etc. We never store configurations in a JAVA class file. Think hard, why is that?
This is because configuration is a static data. It often require hierarchy. It is supposed to be readable. It never requires compilation. It doesn't require knowledge of JAVA programming language. In short, it is a different ball game. Now the question is, how it relates to our discussion?
Now, lets think about a web page. Do you think when we write a web page we write a business logic? Absolutely not. Web page is just a configuration. It is a configuration of hierarchical containers and fields. We need to write business logic for the data that will be captured from and displayed on the web page and not to create the web page itself.
Previous paragraph makes a very very strong statement. This will explain why HTML and XML based web pages are still the most popular ones. XML is the best in business to write configurations. A framework must allow a clear separation of web page from business logic (the goal of MVC framework). By doing this a web designer will be able to apply his skills of visualization and artistry to create brilliant looking web pages just by configuring XMLs and without being bothered about the intricacies of a programming language. Developers will be able to use their best in business JAVA for writing business logic.
Finally, lets talk about the repercussions in direct terms. GWT breaks this principal so it is bound to fail. The cost for developing GWT application will be very high because you will need multiskill programmers to write web pages. The required look and feel will be very hard to achieve. The turn around time of modifying the web page will be very high because of unnecessary compilation. And lastly, since you are writing web pages in JAVA it is very easy to corrupt it with business logic. Unknowingly you will introduce complexities that must be avoided.

You could also consider Grails ("Groovy on Rails") which gives you the benefits of a Rails framework and the use of the Java VM.

Our team recently asked the same question, and we chose to go with GWT, especially since the designer plugin made working with GWT more accessible to non-java experts on the team. Whoever makes this choice, just beware you DON'T use the GWT Designer plugin !! It has not been updated (in at least a year, apparently) to create a GWT application that is compatible with IE8.
Our team had almost completed our application layouts, which were working perfectly in Chrome, FF and Safari. Then they blew up in IE. IE 7 would load partial pages (but not composite includes), and IE8 was not even able to load up the application. It just hung.
The designer plugin has buttons that allow the user to add CellTable widgets that are not IE compatible (CellTable, DeckPanel, Horizontal Panel, Vertical Panel, among others). These will cause intense pain when the layouts have to be re-done in java without assistance from the designer.
Experienced GWT users love it, but the designer plugin will kill you.