Ruby on Rails: JavaScript May 5th, 2015

  • Sample CoffeeScript AJAX request… 
    //This code fetches data from "/test", and then appends the result to the div with an id of results...
$.ajax(url: "/test").done (html) ->
 $("#results").append html
  • Unobtrusive JavaScript is separating the script from the HTML markup
  • Built-in helper methods
    • form_for and form_tag … helps in writing forms 
      // Remote submits the form via AJAX
<%= form_for(@article, remote: true) do |f| %>
 ...
<% end %>

// JS ... tie into the success event
$(document).ready ->
 $("#new_article").on("ajax:success", (e, data, status, xhr) ->
 $("#new_article").append xhr.responseText
 ).on "ajax:error", (e, xhr, status, error) ->
 $("#new_article").append "<p>ERROR</p>"
    • link_to … can use remote: true to use AJAX
    • button_to … can use remote: true to use AJAX
  • Sample AJAX in controller… 
    # app/controllers/users_controller.rb
# ......
def create
 @user = User.new(params[:user])
 
 respond_to do |format|
   if @user.save
     format.html { redirect_to @user, notice: 'User was successfully created.' }
     format.js {}
     format.json { render json: @user, status: :created, location: @user }
   else
     format.html { render action: "new" }
     format.json { render json: @user.errors, status: :unprocessable_entity }
   end
 end
end

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