ESLint v4.0.0-alpha.0 released

We just pushed ESLint v4.0.0-alpha.0, which is a preview release upgrade of ESLint. This release adds some new features and fixes several bugs found in the previous release. This release also has some breaking changes, so please read the following closely.

Note: This version of ESLint is not ready for production use and is provided to gather feedback from the community before releasing the final version. Please let us know if you having any problems or feedback by creating issues on our Github repo or joining our Gitter channel.


This is a summary of the major changes you need to know about for this version of ESLint.


Since this is a pre-release version, you will not automatically be upgraded by npm. You must specify the next tag when installing:

npm i eslint@next --save-dev

You can also specify the version directly:

npm i eslint@4.0.0-alpha.0 --save-dev

Migration Guide

As there are a lot of changes, we’ve created a migration guide describing the changes in great detail along with the steps you should take to address them. Not all ESLint users will be affected by the changes, however, the changes are big enough that we recommend everyone read the migration thoroughly.

New Rules

There is one new rule in this release:

Breaking Changes



Bug Fixes