donot install js2-mode for emacs version < 24.1
donot install js2-mode for emacs version < 24.1

zuoshifan/emacs.d,zuoshifan/emacs.d,zuoshifan/emacs.d,zuoshifan/emacs.d,zuoshifan/emacs.d,YangXin/emacs.d,zuoshifan/emacs.d,zuoshifan/emacs.d,YangXin/emacs.d,zuoshifan/emacs.d,zuoshifan/emacs.d