Develop Reference

What is the Difference between Xamarin and Telerik Platform

This is going to be quite a hectic question and im hoping that you can all Bear with me.
Im having difficulty fully understanding some things about mobile App development.
So my Main question is : What is the difference between Telerik Platform and Xamarin ? Dose it just depending on what you are more comestible with, Like if you are a c# developer and know the .Net framwork, Then use Xamarin or is it alot more complex than that ? As i know that Telerik uses Javascript, so is it more of an open dev based mobile app ?
Which is better for the future of mobile development as i want to move in the right direction.
As an Extra: Has anyone heard of Dart ? i found out about it last week and haven't had much time to Read up on it, but it looks like a web based solution from google.
Dartlang

In Xamarin you can build native applications for Android and iOS system.
It is also possible to write them for Windows Phone.
Xamarin uses C# language.
Apps are created natively using Xamarin wrappers.
There are two options for creating apps in Xamarin:
1) Xamarin.Forms is best for:
Data entry apps
Prototypes and proofs-of-concept
Apps that require little platform-specific functionality
Apps where code sharing is more important than custom UI
2) Xamarin.iOS & Xamarin.Android are best for:
Apps that require specialized interactions
Apps with highly polished design
Apps that use many platform-specific APIs
Apps where custom UI is more important than code sharing
Telerik Platform is good for web developers who want to create mobile apps:
Here you can write html and javascript.
Remember also that your apps on iOS and Android will be displayed in WebView (browser). Only Windows Phone apps can be written in html and javascript natively.
Hope this will help.
Please also see this (I asked about Xamarin and Apache Cordova):
http://www.codeproject.com/Forums/13695/Mobile.aspx

All of the mentioned framework do the same thing in different ways, its totally depends upon your skillset and interest which framework you find easy to understand or find interesting.
Each of those have their market in which you can grow. below are some links may help you.
http://www.telerik.com/campaigns/build-mobile-apps-with-dotnet
https://forums.xamarin.com/discussion/13686/the-future-benefits-of-xamarin-over-other-options-and-mobile-apps-replacing-websites

Dart is a modern open source programming language that allows to write concise code
built-in support for async/await, Future (Promise), Stream (Observable), ...
Supports lots of platforms
Server with the Dart-VM (Windows, OSX, Linux)
in the browser after to-JS transpilation
Android and iOS by Flutter https://flutter.io/
embedded systems by Dartino https://dartino.org/
Dart can be transpiled to JavaScript (to-TypeScript is work in progress)
extensive high-quality standard libraries
dart:html library that for browser abstraction that makes most polyfills redundant
shipped with lots of tools
package manager
analyzer/linter
debugger and profiling tools
test runner
Dartium development browser
...
IDE support
easy integration using the IDE services the analyzer provides
Atom plugin
WebStorm/IntelliJ plugin
...

JavaScript in iPhone programming

I am currently developing apps for the iPhone and iPad with Objective-C. I found some code related to using JavaScript in the iPhone.
Can we create apps more easily and accurately with the help of JavaScript?
Does Apple approve apps created at least partially with JavaScript?
How should one begin learning JavaScript?
Are there any tutorials that can help me to understand and learn JavaScript, particularly for iPhone/iPad programming?

Web Apps
Web Apps are highly optimized special websites that are accessed from any device but still look and feel like a full-fledged application. An early example would be GMail. Here is an old blog post by jQuery's John Resig on early web app development.
1. Can we create apps more easily and accurately with the help of Javascript?
This is a bit mis-leading as the intents may be different. The goal of web apps to hit the widest possible audience with minimal effort, however, you are restricted to non-native functions.
Native functions include use of the device hardware such as camera, gps, touching other apps, notifications etc. There are several libraries that provide a wrapper around your web app to expose these underlying calls but then you must do that for each device. Libraries include: Phonegap, Titanium.
2. Does Apple approve apps created at least partially with JavaScript?
Most certainly! They even have a special section. With most webapps it is just a bookmarklet the user drags to their home screen for quick access. If you want to do the true app in the store you will need a wrapper library as mentioned before to package your app together.
3. How should one begin learning JavaScript?
Out of scope for this question, but Douglas Crockford is one of the better teachers, he has a multi-part video series as well as a book to get you learning the "good parts".
4. Are there any tutorials that can help me to understand and learn JavaScript, particularly for iPhone/iPad programming?
Honestly, it would best to learn javascript first, as it is a prototypical object based puzzle then worry about how to utilize the various frameworks for best mobile performance.
Adding 5. What are some javascript mobile frameworks?
jQuery Mobile
Dojo Mobile
Sencha (Ext) Touch
Wink
iUI
These are just the most common but I would browse each of them a bit as jQuery, dojo and sencha have different approaches on how javascript should be used.

Can we create apps more easily and accurately with the help of JavaScript?. Yes and No. Javascript will allow you to write loose code and draw from a wealth of code floating around, it is less technical than writing in Objective C, however the UI will be less responsive than native and quite a bit more buggy. My advice is if you your not proficient in Javascript then "don't go there".
Does Apple approve apps created at least partially with JavaScript? Apple will frown upon this and you may find that if the App is entirely within the UIWebView you may be rejected, but I have not experienced this (they do sort of state this in their guide).
How should one begin learning JavaScript? Read material from Douglas Crockford first, I really don't agree with half the stuff he says, but to a complete beginner then he will enlighten you. Also start playing with jQuery. Manipulating HTML is painful and this will save you a lot of pain.
Are there any tutorials that can help me to understand and learn JavaScript, particularly for iPhone/iPad programming? You will be essentially be writing for a Safari browser (webkit). Your standard jQuery will get you along the way, but one very important piece of advice - Objective C isn't simple but that doesn't mean that Javascript is. designing UI interfaces for a mobile device will definitely cause you headaches - be under no illusions, even with mobile frameworks/libraries like JQTouch, Sencha and jQueryMobile you will feel the pain!
Good Luck :)

I cannot give you much advice on 1 and 2 except that I've worked on quite a few hybrid apps for iPhone where a webpage was displayed in an iPhone app.
As for questions 3 and 4:
A good place to start learning Javascript is:
http://eloquentjavascript.net/
More advanced sources are:
JavaScript: The Good Parts by Douglas Crockford (must read as mentioned above)
Professional Javascript for Web Developers 2nd Edition, Nicholas C. Zakas
Since the iPhone and iPad use the Safari browser (webkit) you can use Javascript to it's fullest.

Embed a JavaScript engine in an iOS application

I wonder if anyone has successfully ported a javascript engine/interpreter to iOS. I'm writing an iPhone game that I would like to use Javascript as the high-level scripting language (AI, gameplay, etc.), but to do that, I need to compile the JS engine into a static library and link it against my objectiveC program for iPhone OS. There are some candidate JS engine I'm looking at but I couldn't find any successful cases for doing that.
Here're the js engine I was hoping to use for iOS
google's V8 javascript engine
mozilla's SpiderMonkey
The alternative is to use UIWebView's Javascript callback interface, but that requires loading the entire UIWebView into memory and the experiences I heard is that it is usually slow in performance.
Appreciate if anyone had similar experiences of do this or know any references for that!
[UPDATED] as Kostis mentioned, Apple introduced JavascriptCore in WWDC 2013

There are two projects you might be interested in:
JavaScriptCore-iOS
iMonkey
It is absolutely possible to build and ship a JavaScript engine with your iOS app, see http://www.phoboslab.org/log/2011/04/ios-and-javascript-for-real-this-time. Titanium does that, too: https://github.com/appcelerator/webkit_titanium/tree/master/Source/JavaScriptCore.
Also see http://www.phoboslab.org/log/2011/06/javascriptcore-project-files-for-ios.
I've also made a small app that shows how to use JSC on iOS: https://github.com/jfahrenkrug/AddressBookSpy
Enjoy.

For future viewers, now there is the JavaScriptCore framework, introduced in the new iOS 7. It does magic! Wrapping, unwrapping values from/to JS/Objective-C, calling functions, callbacks, everything!
Unfortunately, documentation is really poor at the moment. You can find a presentation from the WWDC 2013 event and some more info in the header files (cmd+click on the header file name in Xcode). There are also some tutorial around the internets which just copy what the guy in the WWDC presentation does.
I've used it for one of my projects, it's really powerful. The only think I didn't like is that it passed objects from JS to ObjC by value, i.e. reference was lost. There might be a workaround for this, but I couldn't find anything without proper documentation.
Hope this will help someone :)

Take a look at the open source project Ejecta, which embeds JavaScriptCore. It provides the HTML5 canvas API, and uses OpenGL & OpenAL.

If you eventually want to port your game to something other than iOS (or you have other reasons to avoid Apple's proprietary interfaces) you can use MuJS. It's a small library providing a JavaScript interpreter that is easy to embed and extend.

Are HTML-based AIR apps equally fast/powerful v. Flex AIR, or just a "lesser" sibling?

I've got a HTML/JS (YUI framework) photo-organizer that needs access to the local FS. Should I move HTML/JS to AIR, or bite the bullet and "port" it to Flex AIR?
I know what the marketing says, but I want the real answer -- what an I "giving up" by going HTML/JS AIR? I'd like to get some feedback from people with deep experience building HTML-based AIR apps.

I don't think you'll see many issues in using the HTML AIR mode, AIR uses the Webkit engine under the covers iirc, which can work well enough, and has most of the same native features of the Flash/Flex built applications. You'll also see most of the HTML5 features you'd find in Safari. I would say if you need animations that Flash will generally run better than Canvas at this point... There's plenty of examples of ExtJS and other frameworks running on AIR.
As to what you are giving up, I don't think you'd lose anything from an HTML to HTML/AIR standpoint. You could gain a lot of what you gain in having an application in general based in Flash over straight HTML. In flex specifically controls and other features can be more readily tweaked than standard HTML controls. The animation tools in Flash are much nicer. ActionScript doesn't line up to JS on a one to one basis, so there may be issues with code. Dealing with remote content/data is actually a little nicer imho in AS over XHR, though only when dealing with XML.
From an administrative standpoint, going to AIR with HTML from an already written application is probably the shortest path. If you REALLY needed to, you could convert later, and a lot of the underlying logic would be worked out. Time to market would be shorter with whatever is closest to what you are already using more often than not.

Not really, since FS access is available with the HTML/JS version. However, the other route does open up some more native support for application development -- Animation for example, richer controls etc which you will have to live without otherwise. You will greatly miss the debugger and the profiler as also the design view when you move to complex applications. Also, note that if you are worried about sharing your source you probably shouldn't use the HTML/JS way.

I want to write a desktop OSX or Windows app in Javascript -- any experiences?

I'd like to write some small applications for Windows and OSX.
Portable is good. For instance, the simple TclKit solution for TCL would work well if I could stand to look at Tcl for any length of time.
I'm considering using Javascript + extensions -- I really like Javascript -- seems to me there should be some way to connect a Javascript engine to WxWin or even the Tk toolset -- it's been done for Perl, Python, Ruby, etc. Why not JS?
Any comments appreciated.

I would rather recommend using Adobe Air execution container, it offers way more capabilities / OS integration features compared to HTA of Microsoft or even XULRunner of Mozilla.

If you want to write a desktop app in Javascript, check out HTA: http://msdn.microsoft.com/en-us/library/ms536496(VS.85).aspx
Here is an example of an app that I wrote a long time ago in HTA: http://www.boltbait.com/htmleditor/
Hope this helps.

If you have experience with HTML+JS web applications, I'd recommend Mozilla XULRunner. It gives you native-looking interface widgets (every piece of Firefox interface is a XUL element), and a workflow similar to building HTML-based interface.
You define the interface using XUL, an XML-based language, so it's almost like writing HTML, minus browser incompatibilities and CSS (you can use CSS, but only if you want). All application logic can be written in JavaScript, but in XULRunner you can do a lot more in JS than in a browser (read/write files, execute system commands, make cross-domain XMLHTTPRequests, and a lot of other stuff).
More: http://xulplanet.com/
A lot of example applications: http://code.google.com/p/xulapps/

Mac OS X users tend to dislike applications that don't follow usability guidelines of the platform (menu must be at top of the screen, standard shortcuts & drag'n'drop must work, "OK" must be at right-hand side of alertboxes, no "Apply" button in prefs and so on).
With one-size-fits-all toolkit this may be very difficult to achieve.
The good news is that there's JavaScript<>Cocoa bridge that can be used to create stand-alone full-featured Mac OS X application in JS – just keep front-end and back-end of your application separate enough to be able to plug different UI for each OS.

Rhino would probably give you access to swing. Though, I don't know how much work would be involved.
On the other hand, building a swing app with JRuby is so easy even a sock puppet can do it, so it shouldn't be too hard.

Definitely if you want to implement it using JavaScript, Adobe Air is the way to go. You will even have support on Linux.

Give Titanium Appceletaror a look: http://www.appcelerator.com/.