The Top 20 Visualforce Interview Questions for Aspiring Salesforce Developers

Visualforce is one of the most powerful features of the Salesforce platform, enabling developers to customize and enhance their organization’s Salesforce implementation As Visualforce skills are in high demand, expect Visualforce-related questions in your next Salesforce developer interview.

In this comprehensive guide, I’ll share the 20 most common and insightful Visualforce interview questions to prep you for success. With over 10 years of Salesforce experience, I provide tips and sample answers to ace your next technical interview.

1. What is Visualforce and why is it useful for Salesforce developers?

Visualforce is a framework that allows developers to build sophisticated, custom user interfaces hosted natively on the Salesforce platform Using a tag-based markup language, Visualforce offers complete control over the UI of apps

Key benefits of Visualforce include:

• Rapid development of responsive, cross-platform web interfaces and mobile apps
• Tight integration with back-end Salesforce data and business logic
• Declarative binding of UI components to data
• Support for modern web standards like HTML5, CSS3, JavaScript
• Enhanced UX with client-side interactivity

For Salesforce developers, Visualforce accelerates development by eliminating the need to build an external UI. And since it’s hosted natively within Salesforce, the UIs can seamlessly interact with Salesforce objects, Apex controllers, and more.

2. How does Visualforce work with the MVC architecture?

Visualforce implements the View layer of the Model View Controller (MVC) architectural pattern. It enables developers to define the UI layout, appearance, and behavior of an app using a markup syntax declarative language.

The Model in MVC refers to the data objects and business logic. In Salesforce, this is handled by standard/custom objects, fields, validation rules, workflow rules, Apex triggers etc.

The Controller acts as an intermediary between the View and Model. In Visualforce, default standard controllers handle basic CRUD while custom controllers in Apex can implement complex logic.

• Model: Salesforce platform objects, fields, business logic
• View: Visualforce markup, HTML, CSS
• Controller: Standard/custom Apex controllers

This separation of responsibilities makes Visualforce extremely modular and maintainable.

3. How do you pass data from a controller to a Visualforce page?

Data can be passed from Apex controllers to Visualforce pages in several ways:

• Controller properties – Define public properties in the controller which can be accessed using the {!propertyName} syntax

• Controller methods – Invoke methods returning data from the page using {!methodName()}

• Page parameters – Pass values from page URL or a redirect into controller methods by defining attributes on the <apex:page> tag

• Page references – Return page reference objects from controller to redirect and pass along data values

• View state – Save data into view state and retrieve it across requests

For example, here is a controller property to display an account name:

// Controllerpublic Account account {get; set;} // Page<p>Name: {!account.Name}</p> 

And a controller method example:

// Controllerpublic Integer getContactCount() {  return [SELECT Count() FROM Contact]; }// Page<p># Contacts: {!getContactCount()}</p>

4. How do you execute server-side logic from Visualforce pages?

To execute server-side logic in Apex from Visualforce pages, use:

• Action methods – Controller methods called on page load or by action components like buttons or links using the action attribute:

<apex:commandButton action="{!saveRecord}" value="Save"/>

• Action functions – Make async calls to controller methods from JavaScript code and handle response:

<apex:actionFunction name="updateRecord" action="{!updateRecord}"/> updateRecord(param1, param2, function(result) {  // handle result});

• Remote objects – Invoke Apex methods imperatively from JavaScript

// Controller@RemoteAction public static String getServerTime() {  return String.valueOf(DateTime.now());    }// JavaScript Visualforce.remoting.Manager.invokeAction(  '{!$RemoteAction.SampleController.getServerTime}',   function(result) {    alert(result);   });

5. How do you implement business logic and data access in Visualforce apps?

Visualforce relies on Apex controllers to implement business logic and data access in applications. Here are some approaches:

• Standard controllers – Provide basic CRUD methods out-of-the-box for standard objects

• Custom controllers – For complex logic and integration, build custom controllers with Apex by extending standard controllers

• Controller extensions – Add logic to standard controllers by extending them in separate Apex classes

• DAO pattern – Implement separate data access classes for managing CRUD and querying

• Service layer – For large apps, introduce a service layer with Apex classes encapsulating business logic

Generally, use standard controllers for simple pages, and custom controllers or controller extensions for complex requirements. Manage data access and app logic in separate Apex classes for modularity.

6. How do you implement security in Visualforce pages and controllers?

Some best practices for implementing security in Visualforce include:

• Enforce sharing rules – Avoid without sharing keywords in Apex classes to respect object permissions

• Use contacts for authentication – Prefer current user’s contact to act on their behalf

• Validate user input – HTML encode and JSENCODE untrusted data before output

• Query with care – Use selective SOQL queries, avoid unfiltered queries

• Restrict DML – Enforce CLS and validate record ownership before updates

• Obscure errors – Don’t display sensitive exception messages on page

• Limit component access – Control access to components using rendered or access attributes

• Minimize sessions – Reset view state after commits to minimize vulnerabilities

• Implement CSRF tokens – Enforce CRSF protection even for GET requests

By following security best practices, the risks of vulnerabilities in your Visualforce implementations can be minimized.

7. How do you implement reusable components in Visualforce?

Reusable components allow the same Visualforce markup to be used across multiple pages. To create a reusable component:

1. Define the component markup in a separate file with .component extension using <apex:component> tags

2. Specify required attributes using <apex:attribute>

3. Reference the component in pages using <c:componentName>

For example:

myComponent.component

<apex:component>   <apex:attribute name="recordId" type="Id" required="true"/>   {!recordId}  </apex:component>

Page

<c:myComponent recordId="{!contact.Id}"/>

Make components dynamic by using attributes for input parameters. Follow a modular approach: break large pages into smaller reusable components.

8. What are some best practices for Visualforce development?

Some best practices to follow for quality Visualforce development include:

• Maintain separation of concerns – keep markup, styling and logic separate

• Use standard components over primitive HTML elements whenever possible

• Implement responsive UIs using CSS media queries or frameworks like Bootstrap

• Follow accessibility standards and use proper markup for screen readers

• Initialize variables and prefetch data in controller constructors

• Use scripts and static resources to enforce encapsulation

• Reduce server trips: use action functions for partial updates

• Keep controller code and markup strongly typed

• Add comments for sections of complex markup

• Use Salesforce Lightning Design System (SLDS) for consistent styling

• Ensure your app works in Salesforce1 mobile app

9. How do you optimize the performance of Visualforce pages?

Some ways to optimize Visualforce performance include:

• Enable caching – Use cache="true" for static content

• Lazy load – Fetch data only when needed with action functions

• Limit client trips – Use action functions over full refreshes

• Reduce elements – Avoid unnecessary tags, styling, markup

• Minimize code – Streamline logic in controllers and extensions

• Optimize SOQL – Avoid nested queries, add filters and limits

• Set page size – For loop components, set a smaller page size

• Asynchronous processing – Use future or queueable Apex for long operations

• Limit view state – Store only required variables, avoid huge JSON blobs