Use mmm-mode to enable EJS Template highlighting in html-mode

html-ejs.el

;; ...

;; Use mmm-mode to enable EJS (http://embeddedjs.com) Template highlighting in html-mode

;; Turn on mmm-mode
(require 'mmm-mode)
(setq mmm-global-mode 'maybe)

;; mmm-mode class for EJS Templates
(mmm-add-classes
 '(
   (html-ejs :submode js-mode :front "<%[#=]?" :back "-?%>"
        :match-face (("<%#" . mmm-comment-submode-face)
                     ("<%=" . mmm-output-submode-face)
                     ("<%" . mmm-code-submode-face))
        :insert ((?% ejs-code nil @ "<%" @ " " _ " " @ "%>" @)
                 (?# ejs-comment nil @ "<%#" @ " " _ " " @ "%>" @)
                 (?= ejs-expression nil @ "<%=" @ " " _ " " @ "%>" @))
        )))

;;; Add html-js, embedded-css and html-ejs to html-mode
(mmm-add-mode-ext-class 'html-mode nil 'html-js)
(mmm-add-mode-ext-class 'html-mode nil 'html-css)
(mmm-add-mode-ext-class 'html-mode nil 'html-ejs)

;; ...