In a vanilla Rails project that doesnt have the cocoon gem could use this approach to handle adding and removing nested attributes entries using fields_for and accepts_nested_attributes_for.

It can be quite difficult to remember how exactly to do this so I showcase it here.

<%= form_for @post do |f| %>
  <div class="comments-wrapper">
    <% f.fields_for :comments do |f2| %>
      <%= render "comment_fields", f: f2 %>
    <% end %>

  <button type="button" class="add-comment">Add Comment</button>

        var uniqueId = crypto.randomUUID();
        // OR
        var uniqueId = + Math.random().toString(36).substring(2);
        // OR
        var uniqueId = $(".comment-container").length;

        var html = "#{j f.fields_for(:comments,, child_index: 'REPLACE_ID'){|f2| render('comment_fields', f: f2) }}";

        html.replace(/REPLACE_ID/g, uniqueId);
      $(document).on("click", ".delete-comment", function(){
        var container = $(this).closest(".comment-container");
<% end %>

### _comment_fields.html.erb

<div class="comment-container">
  <!-- Other comment fields here -->
  <%= f.hidden_field :_destroy %>
  <button type="button" class="delete-comment">Delete Comment</button>

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