js.vim

    " replace 'function' with λ
    au BufNewFile,BufRead *.js syntax keyword javasScriptFunction function conceal cchar=λ
    au BufNewFile,BufRead *.js hi! link javasScriptFunction Conceal
    au BufNewFile,BufRead *.js setlocal conceallevel=2
    " add abbreviations for JS
    " f_
    "  expands to
    " function() {
    " <cursor>
    "
    " }
    " f- expands to
    " function() { <cursor )
    autocmd Filetype javascript iabbr f_ function(){<CR>:}<ESC>?:<CR><ESC>xO
    autocmd Filetype javascript iabbr f- function(){:}<ESC>?:<CR><ESC>xO