Describe Use Cases for JavaScript in a Visualforce Page. PLATFORM-DEVELOPER-II Practice Questions (Page 5)

Questions 21–25

1. 21foundation · easy

   What is a recommended practice for optimizing JavaScript performance in a Visualforce page?

   • AUsing inline event handlers for all elements
   • BMinimizing the number of DOM manipulations
   • CPlacing all JavaScript at the top of the page
   • DLoading all libraries in every page
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2. 22foundation · easy

   A developer wants to update a section of a Visualforce page without a full page reload. Which JavaScript technique is appropriate?

   • AUsing a server-side controller method without JavaScript
   • BUsing a Visualforce action attribute on a component
   • CUsing a page redirect to a new Visualforce page
   • DUsing AJAX to make an asynchronous request and update the DOM
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4. 23foundation · easy

   Which of the following is a common use case for JavaScript in a Visualforce page?

   • AConfiguring email templates for the organization
   • BPerforming client-side form validation before submission
   • CDefining security permissions for user profiles
   • DCreating database tables for custom objects
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5. 24application · medium

   A developer is optimizing a Visualforce page that uses jQuery for several UI enhancements. The page currently loads jQuery in the header and also loads the Salesforce AJAX toolkit. The developer notices that the page load time is slow. Which best practice would most directly improve performance?

   • APlace all JavaScript at the end of the page body to prevent blocking rendering.
   • BWrap all jQuery code in a document ready function to ensure the DOM is fully loaded before execution.
   • CUse jQuery's .each() method to iterate over all elements on the page to ensure they are all enhanced.
   • DLoad jQuery from a content delivery network (CDN) and use a local fallback if the CDN is unavailable.
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6. 25application · medium

   A Visualforce page displays a large table of records. The developer wants to allow users to sort the table by clicking column headers without a page refresh. What is the most appropriate use of JavaScript in this scenario?

   • AUse JavaScript to reload the page with a query parameter that indicates the sort order.
   • BUse JavaScript to capture the click event on the header, sort the data client-side, and re-render the table rows in the DOM.
   • CUse an actionFunction to call a controller method that sorts the data and rerenders the table.
   • DUse a Visualforce commandLink with a rerender attribute to sort the table.
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