How do you get the Ruby on Rails generated id of a form element for reference in JavaScript?

Question

When using the form_for helper and a text_field call, Ruby on Rails will generate a unique id for the element that it outp

Answer 1

You'll want to specify the id yourself. Here generating the id from the object_id of the form guarantees that it won't conflict with another text_field for username in the case of nested forms.

<%= form_for @user do |f| %>
  <%- id = "username_#{f.object_id}" %>
  <%= f.text_field :username, :id=>id %>
<% end %>

<%= javascript_tag do %>
  $("##{id}").doSomethingReallyCool();
<% end %>