A backend for Flymake which uses eslint.  Enable it with M-x
flymake-eslint-enable RET.  Alternately, configure a mode-hook for your
Javascript major mode of choice:

(add-hook 'some-js-major-mode-hook #'flymake-eslint-enable)

A handful of configurable options can be found in the flymake-eslint
customization group: view and modify them with the M-x customize-group RET
flymake-eslint RET.

License: MIT