flycheck.el

(use-package flycheck
  :ensure t
  :config
  (require 'flycheck)
  (add-hook 'after-init-hook #'global-flycheck-mode)

  (add-hook 'flycheck-mode-hook 'flycheck-color-mode-line-mode)
  (add-hook 'flycheck-mode-hook #'flycheck-rust-setup)
  (load-conf "flycheck-reek")
  ;; disable jshint since we prefer eslint checking
  (setq-default flycheck-disabled-checkers
                (append flycheck-disabled-checkers
                        '(javascript-jshint)))

  ;; use local eslint from node_modules before global
  ;; http://emacs.stackexchange.com/questions/21205/flycheck-with-file-relative-eslint-executable
  (defun my/use-eslint-from-node-modules ()
    (let* ((root (locate-dominating-file
                  (or (buffer-file-name) default-directory)
                  "node_modules"))
           (eslint (and root
                        (expand-file-name "node_modules/eslint/bin/eslint.js"
                                          root))))
      (when (and eslint (file-executable-p eslint))
        (setq-local flycheck-javascript-eslint-executable eslint))))
  (add-hook 'flycheck-mode-hook #'my/use-eslint-from-node-modules))