Describe Use Cases for JavaScript in a Visualforce Page. PLATFORM-DEVELOPER-II Practice Questions (Page 1)

Questions 1–5

1. 1expert · hard

   A Visualforce page displays a list of records with a 'Refresh' button. When clicked, the page should fetch the latest data from the server and update the list without a full page refresh. The developer is considering two approaches: using a JavaScript remoting call to a @RemoteAction method, or using an actionFunction with a rerender. Which approach is more appropriate and why?

   • ANeither; you should use a full page reload to ensure data consistency.
   • BBoth are equally appropriate; the choice depends on personal preference.
   • CJavaScript remoting, because it provides more control over the response and avoids the overhead of rerendering the entire page.
   • DActionFunction with rerender, because it is simpler and automatically handles view state updates.
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2. 2foundation · easy

   Which practice helps avoid conflicts between JavaScript libraries in a Visualforce page?

   • AUsing the same variable names across libraries
   • BUsing global variables for all functions
   • CWrapping code in an immediately invoked function expression (IIFE)
   • DLoading all scripts in the page header
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4. 3application · medium

   A developer is building a Visualforce page for a custom object called 'Project__c'. The page displays a list of related 'Task__c' records. The requirement is that when a user clicks a checkbox on a task row, the row's background color changes immediately to indicate completion, without a page refresh. Which JavaScript approach should the developer use?

   • AUse JavaScript to replace the entire page's innerHTML with a new HTML string that includes the updated row style.
   • BUse an actionFunction to call a server-side method that updates the task record and then refreshes the page.
   • CAttach an onchange event handler to the checkbox that uses DOM manipulation to add a CSS class to the row.
   • DWrap the checkbox in an outputPanel with a rerender attribute that re-renders the row on change.
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5. 4application · medium

   A Visualforce page needs to display a count of related records for a list of accounts. The developer wants to fetch the counts asynchronously after the page loads and update the display without a page refresh. Which approach is most efficient?

   • AUse multiple JavaScript remoting calls, one for each account, to fetch the counts individually.
   • BUse a single JavaScript remoting call to a @RemoteAction method that returns the counts for all accounts, then update the DOM.
   • CUse a Visualforce actionPoller to periodically fetch the counts for all accounts.
   • DUse an actionFunction that rerenders the entire page with the counts.
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6. 5expert · hard

   A Visualforce page has a custom lookup field. When the user types in the field, the page should display matching records in a dropdown. The developer wants to implement this using JavaScript. The page also needs to handle cases where the user types quickly, to avoid sending too many requests. Which technique should be used?

   • AUse a timer that triggers the AJAX call every 5 seconds to update the results.
   • BUse a throttle function to limit the number of calls to one per second, regardless of typing speed.
   • CUse a debounce function to delay the AJAX call until the user stops typing for a short period.
   • DMake an AJAX call on every keystroke to ensure the results are always up to date.
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