Enable parameter/snippet jumping.

init.vim

@@ -52,23 +52,28 @@ set foldmethod=syntax
 set scrolloff=7
 
 " CoC settings
+function! CheckBackspace() abort
+	let col = col('.') - 1
+	return !col || getline('.')[col - 1]  =~# '\s'
+endfunction
+
 inoremap <silent><expr> <TAB>
       \ coc#pum#visible() ? coc#pum#next(1) :
+	  \ coc#expandableOrJumpable() ? "\<C-r>=coc#snippet#next()\<CR>" :
       \ CheckBackspace() ? "\<Tab>" :
       \ coc#refresh()
-inoremap <expr><S-TAB> coc#pum#visible() ? coc#pum#prev(1) : "\<C-h>"
-"inoremap <expr> <Tab> pumvisible() ? "\<C-n>" : "\<Tab>"
-"inoremap <expr> <S-Tab> pumvisible() ? "\<C-p>" : "\<S-Tab>"
-nmap <C-a> :CocAction<CR>
+inoremap <silent><expr> <S-TAB>
+      \ coc#pum#visible() ? coc#pum#prev(1) : "\<C-h>"
+	  \ coc#expandableOrJumpable() ? "\<C-r>=coc#snippet#prev()\<CR>" :
+	  \ CheckBackspace() ? "\<S-Tab>" :
+	  \ coc#refresh()
 let g:coc_disable_startup_warning = 1
 
 inoremap <silent><expr> <CR> coc#pum#visible() ? coc#pum#confirm()
                               \: "\<C-g>u\<CR>\<c-r>=coc#on_enter()\<CR>"
 
-function! CheckBackspace() abort
-	let col = col('.') - 1
-	return !col || getline('.')[col - 1]  =~# '\s'
-endfunction
+let g:coc_snippet_next = '<Tab>'
+let g:coc_snippet_prev = '<S-Tab>'
 
 func! s:my_colors_setup() abort
 	" this is an example