The jQuery team announced the first jQuery 3.0 and jQuery Compat 3.0 alpha releases in July 2015. This is a historical release note, not a recommendation to install those alpha packages now.
Why there were two builds#
The announcement separated the modern-browser build from a Compat build intended to retain older browser support. That distinction reflected the browser landscape of the time, including Internet Explorer versions that modern projects should not assume they must support.
The original jQuery announcement is the source for the release details. The 3.0 final announcement records the later final release.
Reading the note today#
An alpha release is useful for compatibility testing, not as a default dependency copied from an old article. For a maintained application, check the versions supported by its framework and test its own plugins and integration code.
If you are choosing dependencies for a new project rather than maintaining an existing jQuery application, start with the project-language guide and the requirements of the actual interface.
