init

nvim/after/ftplugin/jsonc.lua

@@ -0,0 +1,11 @@
+-- When creating a new line with o, make sure there is a trailing comma on the current line
+vim.keymap.set("n", "o", function()
+  local line = vim.api.nvim_get_current_line()
+
+  local should_add_comma = string.find(line, "[^,{[]$")
+  if should_add_comma then
+    return "A,<cr>"
+  else
+    return "o"
+  end
+end, { buffer = true, expr = true })