AccordionNewsList widget: Implement the client-side functionality 
After you implement the markup, you must add the code that selects an element by ID and associates it as a jQueryUI accordion. To do this, add a JavaScript file to your widget and name it AccordionNewsList.js.
EXAMPLE: For more information about the JavaScript of the widget, see AccordionNewsList.js in Sitefinity documentation-samples on GitHub.