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Pro Easy data binding
Pro Easy to learn
Has a low entry barrier and an easy learning curve. It's especially easy to learn for beginners.
Pro Built in templating
Bindings in Knockout can also be used to control the generated structure of the HTML. There are bindings provided to allow for iteration and conditionals. The structure of the html reflects the structure of the data so iterative elements are bound to arrays in the data model. Having the HTML structure maintained by bindings keeps the templating simple, easy to read, and maintain.
Knockout also allows for string based templating so you can use whatever templating library you prefer.
Pro Legacy browser support
Supports a large number of browsers, including IE6.
Pro Great documentation
The excellent tutorials with built-in exercises are a great learning experience, even for people without prior MVVM and data binding experience.
Pro Lightweight and plays nicely with other libraries
Pro Dynamic models help with keeping the code simple and clean
Models in Knockout can be watched to keep the page data up to date by using observable objects. The observables notify Knockout when data is changed and automatically updates the page when this happens. By having Knockout maintain this relation, it keeps the front end code cleaner and simpler, and by enforcing a consistent pattern with observables the methodology can be more robust.
Pro Very flexible
One can do a lot of things and it keeps self references and other types of loops under control.
Pro It's only a library
Knockout does one thing, and does it well. It doesn't try to take on more than one area. It does MVVM data binding and that is it.
Pro Simple manageable modules
Using components is a great way of breaking up large modules into simpler ones.
Pro Out of the box Typescript support
Full support for Typescript built in
Pro Conventions over configurations
Configured to give you the most common use cases by convention, which means you only need to change the default configuration for edge cases. This means that for normal cases far less boiler plate code has to be written.
Pro Out of the box ES6 support
Aurelia includes native support for ES6 and even comes with a Gulpfile which helps with transpiling ES6 code to ES5.
Pro Good binding system
Clear, intuitive and HTML/SVG compliant binding syntax.
Default binding => value.bind
One Way binding => value.one-way
Two Way binding => value.two-way
One Time binding => value.one-time
Pro Allows developers to build their application however they want
Aurelia is extremely unopinionated and was designed to be highly modular. This gives the developer the freedom to develop their application however they want, without forcing them in paradigms or rules predefined by the framework. Likewise, any of the individual components can be swapped out if so desired.
Pro Agnostic code
Pro Standards compliant
Aurelia developers always try to keep within existing and emerging Web Standards, making it easier for developers to follow best practices in web development.
Pro Easy to learn
Learning aurelia basically means learning EcmaScript and HTML, since aurelia is designed for standards compliance. Also, aurelia embraces upcoming ES language features by convention, such as ES class decorators for dependency injection, encouraging clean architecture and future-proof code.
Pro Variable binding helps with self-documenting the code
Aurelia.js consists of modules that can be used as a full framework or separately.
Pro Great documentation
One of the most crucial pieces of any new technology or framework is the documentation. At present even though Aurelia is pre-beta, the documentation is pretty complete. There are code examples missing and whatnot, but for the most part it is concise and makes the main parts of the application easy to understand.
Pro Full commercial support
Aurelia is officially backed by Durandal Inc. and has commercial and enterprise support is available.
Pro Plays well with other frameworks
Aurelia can be used alongside of React and Polymer, since it is designed for interoperability. In practice, this means Aurelia developers can use React components by including an Aurelia custom element:
It also works well with Polymer, since they are both based on the WebComponents standards:
Pro Data binding choices with sane defaults
Aurelia defaults to one-way data binding, alining with conventional wisdom. However, there are times when two-way data binding proves useful, such as binding an input widget with a view-model. Aurelia makes two-way data binding available to developers and uses it by convention when appropriate.
Pro Powerful helper CLI available
The CLI helps rapid creation of projects with generators, building, deploying and hot reloads. Webpack should be coming soon.
Pro Growing community
The Aurelia community is growing at a great pace. Still doesn’t rival the big players line Angular or React, but the answer to an Aurelia issue is a quick question away on their Discourse.
Con Slower than others when amount of objects grows
Knockout has a bad performance when the dealing with large amount of objects. You can see more here.
Con Can become complex once the application grows large
Knockout leaves the application structure to the developer and it can become quite complex and unmanageable in the hands of a beginner once the application grows large and complex.
Con Two way binding requires a little extra work
When allowing users to edit existing data, the two-way binding of observables means you'll need to have to save original values before they're edited, to make comparisons or revert if the user cancels the action.
Con Needs more support from the community
It would be great to have a lot of plugins made by the community, or video tutorials from experiences when using it. Hopefully in the near term future.
Con No big success stories yet
There are no notable big web products build with aurelia yet
Con Two-way data binding is often considered an anti-pattern
Two-way data-binding means that a HTML element in the view and an Angular model are binded, and when one of them is changed so is the other. One-way data-binding for example does not change the model when the HTML element is changed.
This is a rather controversial subject and many developers consider two-way data binding an anti-pattern and something that is useless in complex applications because it's very easy to create complex situations by using it and being unable to debug them easily or understand what's happening by just looking at the code.