How is the vim taglist plug-in configured?

  question, vim

My relevant configuration in. vimrc is as follows:

filetype on
 
 let Tlist_Ctags_Cmd = '/usr/bin/ctags'
 Let Tlist_Show_One_File = 1 "does not display tag of multiple files at the same time, only the tag of the current file is displayed
 Let Tlist_Exit_OnlyWindow = 1 "exit vim if taglist window is the last window
 Let Tlist_Use_Right_Window = 1 "displays the taglist window in the right window
 
 map <F8> :!  ctags -R --languages=javascript,java,python<CR>

However, when F8 is applied, the javascript function list cannot be established and there is no error prompt. There is a tags file under the current path of the code. When F8 is pressed, the file is updated with js related content. However, when displaying the tags list in vim, only the file name of the code has no function list.
Why?

Well, I found the problem myself.

Ctags only supports such styles as functiona () {}.
However, my code is written in the way varaa = function () {}, so it cannot be displayed.