A snippet that defines a `MarkdownTOC` command that creates a table of contents in the current markdown file at the cursor. nothing fancy

markdowntoc.lua

vim.api.nvim_create_user_command("MarkdownTOC", function()
    if vim.bo.filetype ~= "markdown" then
        print("This is not a markdown file")
        return
    end

    -- Extract the hashtags using grep
    local hashtags = vim.fn.systemlist("grep -oE '^#+.*' " .. vim.fn.expand("%"))

    local toc = ""
    for _, hashtag in ipairs(hashtags) do
        -- the level determines the number of spaces before the list element (based on the amount of hashtags)
        local level = string.len(string.match(hashtag, "^#+"))
        local text = string.match(hashtag, "^#+%s*(.*)%s*$")
        local anchor = string.lower(string.gsub(text, "%s+", "-"))
        -- level is decreased by one because we want to start at root level
        toc = toc .. string.rep("  ", level - 1) .. "- [" .. text .. "](#" .. anchor .. ")\n"
    end

    vim.api.nvim_paste(toc, true, -1)
end, { nargs = 0 })