js2-additional-externs

gistfile1.el

(defun um-js-additional-externs ()
  (let ((jshintrc (expand-file-name ".jshintrc"
                                    (locate-dominating-file
                                     default-directory ".jshintrc"))))
    (when (file-readable-p jshintrc)
      (message "Using jshintrc file: %s" jshintrc)
      (let ((jshintrc-data (json-read-file jshintrc)))
        (setq js2-additional-externs
              (union js2-additional-externs
                      (mapcar #'symbol-name
                              (mapcar #'car
                                      (cdr (assq 'globals jshintrc-data))))))))))

(add-hook 'js2-mode-hook 'um-js-additional-externs)