I have been developing a quiz app for practice with a more complex schema interface. I wanted to dive deeper into CoffeScript and found the opportunity while trying to figure out how a student can add an answer to a given quiz. If a checkbox for a given answer is checked, I wanted the remaining checkboxes to disappear. Also, if the student checked the incorrect box, the browser should render all checkboxes again. Here is my code.

{% codeblock questions.js.coffee lang:js %}

$('form').on 'click', '.checker', (event) ->
    boxes = $(":checkbox:checked")
    nboxes = $(":checkbox:not(:checked)")
    if boxes.length == 1
        $('.checker_label').hide()
        nboxes.hide()
    if boxes.length == 0
        $('.checker_label').show()
        nboxes.show()

{% endcodeblock %}

... and the view

{% codeblock _form.html.haml lang:ruby %}

Quiz: = @quiz.name

= form_for @question do |f| = f.hidden_field :quiz_id, value: @quiz.id = f.label “What is your question?” = f.text_field :content %br %fieldset = f.fields_for :answers do |builder| = builder.label :content, “Answer” = builder.text_field :content = builder.label “Correct answer?”, class:‘checker_label’ = builder.check_box :is_correct, class: ‘checker’ %br = link_to_add_fields “Add an answer choice”, f, :answers %br = f.submit

{% endcodeblock %}