jQuery disable/enable submit button

Question

I have this HTML:

How can I do something li

Answer 1

Here's the solution for file input field.

To disable a submit button for file field when a file is not chosen, then enable after the user chooses a file to upload:

$(document).ready(function(){
    $("#submitButtonId").attr("disabled", "disabled");
    $("#fileFieldId").change(function(){
        $("#submitButtonId").removeAttr("disabled");
    });
});

Html:

<%= form_tag your_method_path, :multipart => true do %><%= file_field_tag :file, :accept => "text/csv", :id => "fileFieldId" %><%= submit_tag "Upload", :id => "submitButtonId" %><% end %>