js-fly.el

(defun current-sentence ()
  (interactive)
  (replace-regexp-in-string "\n" ";"
    (substring-no-properties
      (or (sentence-at-point)
          (save-excursion
            (backward-sentence)
            (sentence-at-point))))))

(defun commit-last-js ()
  (interactive)
  (let ((sentence (current-sentence)))
    (with-current-buffer "*shell*"
      (insert sentence)
      (comint-send-input))))

(defun eval-last-js ()
  (local-set-key (kbd "C-x C-e") #'commit-last-js))

(add-hook 'js-mode-hook #'eval-last-js)