This is the first version of Sizzle that has been published to npm by the jQuery team.
Compatibility note: The Ender team has graciously agreed to hand over the name "sizzle" on npm to the jQuery team, which allows us to publish the official Sizzle on npm under its name. The npm package formerly known as "sizzle" included a bridge for Ender. From version 2.0 onwards, this bridge will not be included. However, we don't want to break anything, so none of the earlier versions will be removed from npm. Another package will be published to npm soon that includes the Ender bridge. We will then provide a link to that package in Sizzle's README.
Other than that, upgrading to version 2.0 should not be a problem.