In September 2017, Microsoft announced the availability of Feature Pack 2 for SharePoint Server 2016. This update includes initial support for the SharePoint Framework-based customizations in locally hosted SharePoint 2016 farms.

The update is available through the September 2017 Public Update, and the bits can be downloaded for your SharePoint 2016 farm from https://technet.microsoft.com/en-us/library/mt715807%28v=office.16%29.aspx.

As the support does not--at least in the initial release--have parity with all the SharePoint Framework functionalities Microsoft supports with SharePoint Online, it is more limited but still very usable. Now, developers can target their code for on-premises and cloud-based deployments, with minimal, if any, changes to their code. In time, Microsoft will provide further updates to SharePoint 2016, which makes using SPFx a logical choice as a development approach.

Customers who are still running older versions of SharePoint, such as 2013 or 2010, do not get support for the SharePoint Framework. This might require too much work for Microsoft to make it a viable approach, and most customers are typically either planning to migrate to SharePoint Online or upgrade to a newer SharePoint version in the future. As discussed in the earlier chapters of this book, customizations created with models other than SPFx are not automatically migrated as part of a version change and will require additional work or even rewrite. In these cases, developers should switch to the SharePoint Framework, as it is the current model that evolves and provides support for both cloud and on-premises platforms.