simple form - Add character counter in simple_form in Ruby on Rails -

i use simple_form gem , want simple character counter on text field. told, might work:

add form:

<%= f.input :body, id: "body-field" %> <span id="body-count">0 characters</span> 

and javascript:

$("#body-field").on("keyup", function(){ length = $(this).val().length; $("#body-count").html(length); }); 

i got information here (attention: full of advertisement): http://www.sohua.xyz/questions-full/4320915/how-do-i-implement-a-basic-character-counter-in-a-simple-form

i did this, nothing happens. here actual code chapters/new.html.erb:

    <%= simple_form_for([@book, @book.chapters.build]) |f| %>     <%= f.input :chaptertitle %>     mininmum amount of characters: <%= @book.min_length %> maximum amount of characters: <%= @book.max_length %>     <%= f.input :chaptercontent, id: "body-field" %>     <span id="body-count">0 characters</span>     <%= f.input :author %>     <%= f.button :submit %> <% end %>      <script>       $("#body-field").on("keyup", function(){         length = $(this).val().length;         $("#body-count").html(length);       });     </script> 

can give me advice, how work?

you need wrap code in jquery document ready function:

$(function() {   $("#body-field").on("keyup", function(){     var length = $(this).val().length;      $("#body-count").html(length);   }); }); 

why don't use existing library instead? https://github.com/dtisgodsson/jquery-character-counter