Infusion, as a proper framework, has been around for nearly seven years now. Along the way, it has evolved and changed a lot, yet we worked very hard to ensure backwards compatibility and incremental upgrades for our users. We haven't always managed to avoid API breakage, but we've tried to make the upgrade process as seamless as possible. The 1.x line of Infusion has been going strong since 2009. Since then, lots of new features that help to extend our declarative, context-aware approach (such as the IoC system, model transformation, and model relay system) have been introduced and proven in real-world software.
But as Infusion's accessible programming strategies have evolved, carrying around legacy code for backwards compatibility has slowed us down. For the past couple of years, we've been carefully deprecating old APIs and planning a new line of releases that will allow us to shed old code and more clearly describe the status of a release to users. We also decided to adopt the semver approach to release numbering and to publish npm packages more frequently.
As of August 2015, the Infusion 2.x line is now in the master branch of the Infusion repository, where it will be our primary development focus. These changes remove a significant amount of legacy code, simplify the process of declaring components, improve the performance and memory management of the framework, and provide the foundation for new debugging and authoring tools. The master branch also breaks compatibility with code written to the Infusion 1.5 APIs, so it will require some work to upgrade to. We are working on documentation that describes the changes and how to upgrade a 1.5 application, which will be available prior to the first 2.x release. We have also created a maintenance branch for changes to the previous version.
We will be releasing a series of 2.0 betas over the coming months for advanced users. The new code our master branch has been significantly tested across all supported browsers (the latest stable releases of Firefox, Chrome, Safari, and IE) and is ready to be used, though Infusion 1.5 remains the latest official stable release.