Describe Use Cases for JavaScript in a Visualforce Page. PLATFORM-DEVELOPER-II Practice Questions (Page 4)

Questions 16–20

1. 16application · medium

   A Visualforce page has a form with several required fields. The developer wants to validate the fields on the client side before the user submits the form, to provide immediate feedback. Which JavaScript approach is most appropriate?

   • AUse a Visualforce actionFunction to call a controller method that validates the fields and rerenders the page with errors.
   • BUse the required attribute on each input field and rely on the browser's built-in validation.
   • CUse JavaScript to disable the submit button until all fields are filled, checking on every keystroke.
   • DAttach a submit event handler to the form that checks each field's value and displays error messages if any are empty.
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2. 17application · medium

   A developer wants to include the jQuery library in a Visualforce page. The page is used in a managed package that will be installed in many orgs. What is the best practice for including jQuery to avoid conflicts with the host org's scripts?

   • AUse a static resource to host a specific version of jQuery and load it with a script tag, then use noConflict.
   • BInline the entire jQuery library directly into the Visualforce page markup.
   • CLoad jQuery from a public CDN without any fallback.
   • DUse the Salesforce AJAX toolkit's built-in jQuery to avoid external dependencies.
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4. 18foundation · easy

   Which JavaScript method is used to programmatically attach an event handler to an element in a Visualforce page?

   • Aelement.on()
   • Belement.addEventListener()
   • Celement.attachEvent()
   • Delement.bind()
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5. 19foundation · easy

   Which JavaScript method is used to change the text content of an element in a Visualforce page?

   • Aelement.content
   • Belement.value
   • Celement.text
   • Delement.innerHTML
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6. 20expert · hard

   A developer is integrating a third-party JavaScript library into a Visualforce page. The library is large and is only needed for a specific user action. The developer wants to minimize the initial page load time. Which approach is most appropriate?

   • ALoad the library dynamically only when the user performs the action that requires it.
   • BInline the library directly into the page to avoid an extra HTTP request.
   • CLoad the library in the page header using a script tag.
   • DLoad the library in a static resource and reference it in the page, but only if it is used.
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