mmm-vue-js2.el

(defun mmm-mode-restart! ()
  (interactive)
  (widen)
  (let ((ext (file-name-extension (buffer-name))))
    (cond ((string= ext "jade")
           (jade-mode))
          ((string= ext "vue")
           (html-mode))
          (t nil))
    (mmm-mode-off)
    (mmm-mode-on)
    (message "mmm-mode restarted!")))

(define-key mmm-mode-map (kbd "<f6>") 'mmm-mode-restart!)
(define-key pug-mode-map (kbd "<f6>") 'mmm-mode-restart!)
(define-key jade-mode-map (kbd "<f6>") 'mmm-mode-restart!)
(define-key html-mode-map (kbd "<f6>") 'mmm-mode-restart!)

(defun narrow-to-js ()
  (interactive)
  (save-excursion
    (goto-char (point-min))
    (let* ((beg (progn (re-search-forward "<script[^>]*> *" nil :no-error)
                       (right-char 1)
                       (point)))
           (end (progn (re-search-forward "</script>" nil :no-error)
                       (left-char 9)
                       (point))))
      (narrow-to-region beg end)
      (js2-mode)
      )))

(define-key mmm-mode-map (kbd "<f7>") 'narrow-to-js)
(define-key pug-mode-map (kbd "<f7>") 'narrow-to-js)
(define-key jade-mode-map (kbd "<f7>") 'narrow-to-js)
(define-key html-mode-map (kbd "<f7>") 'narrow-to-js)

(define-key js2-mode-map (kbd "<f6>") 'mmm-mode-restart!)