Magento Custom Block for Javascript

Question

Using Magento, I need to pass values from the database to javascript in json in a custom module. I am avoiding inline javascript due to CSP. I followed http://www.pierrefay.com/magento-create-block-44

I am having trouble with the type attribute for the block in the layout file. When I use page/html my javascript template file displays, but sends a text/html header instead of a text/javascript which I believe is a xss risk.

When I try a custom type, like auction/history, the javascript layout does not load. Instead it shows a blank page with the standard shop design. Below are my files

app/code/local/Mymodule/Auction/etc/config.xml

Here I have a custom product view page in the blocks in addition to the new block I am trying to use for the javascript.

<config>
...
  <frontend>
     <routers>
        <routeurfrontend>
            <use>standard</use>
            <args>
                <module>Mymodule_Auction</module>
                <frontName>auction</frontName>
            </args>
        </routeurfrontend>
     </routers>
     <layout>
       <updates>
            <auction>
                 <file>history.xml</file>
             </auction>
        </updates>
     </layout>
  </frontend> 

  <global>
    <blocks>
        <Mymodule_Auction>
            <class>Mymodule_Auction_Block_Catalog_Product_View</class>
        </Mymodule_Auction>
        <catalog>
            <rewrite>
                <product_view>Mymodule_Auction_Block_Catalog_Product_View</product_view>
            </rewrite>
        </catalog>
        <auction>
                <class>Mymodule_Auction_Block</class>
        </auction>
    </blocks>

     ... (code for models and helpers) ...

  </global>
</config>

app/design/frontend/Mymodule/default/layout/history.xml If I change the type="auction/history" to "page/html" it displays but with text/html header instead of text/javascript

<layout version="0.1.0">
     <default>
          <reference name="content"></reference>
      </default>
    <auction_index_history>  
        <reference name="content">
            <block type="auction/history" template="auction/history.phtml" />
        </reference>
    </auction_index_history>  
</layout> 

app/code/local/Mymodule/Auction/Block/History.php

<?php
class Mymodule_Auction_Block_History extends Mage_Core_Block_Template
{
     public function methodblock()
     {
         return ‘informations about my block !!’ ;
     }
}

Answer 1

I think you're mistaking Block and controllers.

A block is only a part of your pages. A controller tells how your page should be rendered in the browser.

About your question on the Block : when you need to create a new template without any related Block method, you should use core/template . This block is the top one ( html/page inherits core/template but with added logic that you might not want)

If you need some custom logic (Block methods), create a php Block class that inherits Mage_Core_Block_Template

And about you're header question : if you output only JSON, you should force the output of JSON using a controller and the method :

$this->getResponse()->setHeader('Content-type', 'application/x-json');