Change label based on selected dropdown [Ruby on Rails 4.2]

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I have a table called network it has the column type and number.

I use this select_tag to get a list of all my network names:

<%= select_tag('NetworksList', options_from_collection_for_select(Network.all, :id, :name))%>

I also have 2 label fields that I want to populate with information dynamically:

<p>Network Type: <%= content_tag('span', "", id: 'NetworkType') %></p> <p>Network Number: <%= content_tag('span', "", id: 'NetworkNumber') %></p>

When the user selects a network from the dropdown list of network names, I want to show the selected item's type and number in the fields named NetworkType and NetworkNumber. I would like this to render in the view immediately after the user selects a dropdown. How would I do this?

I am getting the current error in js console, TypeError: network_details[network_index] is undefined help?