When comparing Backbone vs Sencha Ext JS, the Slant community recommends Backbone for most people. In the question“What are the best Angular.js alternatives?” Backbone is ranked 7th while Sencha Ext JS is ranked 10th. The most important reason people chose Backbone is:
A lightweight view class is provided but there is no default templating method implemented. Because views are minimal it allows for much more freedom to implement views however you would like, and because of this freedom it's possible to write views to more uniquely adapt to a problem. User interactions are done within an events object that allows these interactions to be segregated from the rest of the view code which makes the behavioral aspect of the view easier to read and manage.
Ranked in these QuestionsQuestion Ranking
Pro Gives you the freedom to implement views however you want
A lightweight view class is provided but there is no default templating method implemented. Because views are minimal it allows for much more freedom to implement views however you would like, and because of this freedom it's possible to write views to more uniquely adapt to a problem.
User interactions are done within an events object that allows these interactions to be segregated from the rest of the view code which makes the behavioral aspect of the view easier to read and manage.
Pro Can be combined with any library you want
Pro Large community
Backbone has existed longer than most frameworks, and has a large following of users and projects using it as a framework.
Pro You can call underscore.js methods directly on Backbone objects
Backbone collections and models are extended by underscore.js method allowing you to call underscore methods directly on the Backbone objects.
Pro Easy to interface with the API
Backbone provides Model and Collection classes that provide strong analogs to restful resources. These strong analogs allow you to interface more naturally with the API, and makes it easier to write custom behaviors for more complicated API interactions.
Collections provide a variety of powerful manipulation methods that are integrated from the underscore library, that allow you to manipulate, sort, and filter collection data easily.
Pro Easy to implement complex user interaction
Because all the state is managed by Models and Controllers, and they are extendable objects, you can isolate all the state logic onto those objects allowing the rest of the application to not worry about it. The app is simplified to just taking in input to modify the Models and Controllers, and updating the views to reflect them, but none of the state needs to be a concern outside of the Model and Controller classes.
Pro Doesn’t force you into a particular coding style or paradigm
There is no “magic” happening below the surface: the source code is clear, readable and well commented. Backbone is also “lightweight” in the sense that it doesn’t require a ton of buy-in to use. It can be easily integrated into an existing page, and you can choose to only use certain components of the library (Views without Models or Collections, for example). While there are many frameworks that seem to be faster to get started with, Backbone’s lack of surprises, clear documentation, speed & flexibility make it a good fit for all types of apps.
Pro Extendable with plugins
Because Backbone is so simple, and the different components are very well isolated, it is very easy to extend the functionality of Backbone. If you're writing your own extended code it's easy to keep it separated out, and share with the community.
The community also has many plugins already available, which you can pick and choose to use to fit your programming style.
Pro Easy to abstract interaction
All Backbone classes extend an events class that allows for listening and triggering functionality. Because all classes implement events by default it is easier to provide asynchronous communication between objects, and it allows better abstraction of interaction so the event emitting object does not need to know the structure or existence of the receiving object.
Pro Comprehensive documentation
The Sencha documentation is comprehensive, with detailed documentation and a number of examples displaying the various widgets, tools and themes.
Pro Supports MVC and MVVM development
Pro Supports Web and Mobile deployment out of the one framework or codebase
Pro Support for easy theming of applications
Pro Visual Design tool available
The Sencha Architect product allows you to visually build your application, or rapidly prototype a system.
Pro IDE Plugins available
A number of plugins are available for some of the commonly used IDEs (eg: JetBrains, Eclipse, Visual Studio), providing templates, refactoring support, hinting and code completion/generation, as well as management of includes and other time-saving features.
Pro Charting package included
Con Requires more coding compared to other frameworks
Because many features are not provided out of the box, you either have to write more base class code to get those features, or find a plugin that provides them in a way you like.
It does not provide much structure either, things like memory management must be kept in mind by the developer, also the lack of view lifecycle management makes state changes prone to memory leaks.
Con Can easily lead you to spaghetti code
Heavy event-binding can lead to unmanageable spaghetti mess. BB tempts users to overuse it for no reason.
Con No data binding
Backbone does not have data binding support. However, there are some libraries that can be implemented in order to have data binding in Backbone. Such as Epoxy
Con Sencha CMD is bloated and frustrating to work with
To do any meaningful development, you are stuck with CMD. There is a gulp task that will handle the JS concatenation, but there is nothing outside of CMD that can handle theming in their ecosystem.
In addition, CMD is based on Java, and is very heavy to run (600MB+ on Windows 10 to watch for changes in the application and recompile).
Con Sencha CMD (their CLI) is under documented, and out of date
Their latest release of CMD changed some configuration locations, but the documentation was not updated to reflect this. There is no reference guide on the json configuration files, other than the (unfortunate use of) comments in the generated json files.
Con They use proprietary extensions to SASS, making it incompatible with anything but their Fashion processor
On the plus side, you do not have to install ruby alongside CMD for more recent versions of ExtJS. However, their Fashion processor seems to only be available through CMD.
Con Too often breaking changes between versions. They have little concept of backwards compatibility
Compounded by the fact that there are now two "toolkits" in the same "version" of ExtJS, with certain components not existing in one vs the other.
Con The IDE tools are not sold separately - you must purchase the appropriate license pack
You get all the IDE plugins, even if you only need one. They should offer sell them individually, or continue to bundle them with a dev license pack.
Con Difficult to integrate with 3rd party software
Any third party library you wish to include has to be wrapped in some sort of component adapter. You have to do a lot of tweaking to get the build process right if you want the 3rd party lib to be bundled into your application in the right order.
Con Can be expensive
The framework is a commercial package, and the recent decision to start with a minimum of 5 users may rule out smaller developer teams or startups. Recently, they have started a program that allow essentially what are contractors to purchase single licenses, but not individual, independent developers.