Salesforce Lightning Web Component (LWC) Interview Questions and Answers
1. What is a Lightning Web Component (LWC)?
Lightning Web Component is a Salesforce programming model that leverages modern web standards to develop components for the Salesforce Lightning Platform.
2. What are the key features of Lightning Web Components?
Key features include reusability, encapsulation, performance optimization, and compatibility with modern web standards.
3. How do you pass data from a parent component to a child component in LWC?
You can pass data from a parent to a child component using properties, which are annotated with the @api
decorator in the child component.
4. How can you handle events in LWC?
You can handle events using the @wire
decorator, which binds a component’s property to a value from an Apex method.
5. What is the purpose of the @wire
decorator in LWC?
The @wire
decorator is used to wire a component’s property to a data source, such as an Apex method or a field on a record.
6. What is the role of the Lightning Data Service (LDS) in LWC?
Lightning Data Service provides a standard way to access and manipulate Salesforce data in Lightning Components, including LWC.
7. How do you make an HTTP callout from a Lightning Web Component?
You can use the fetch
API to make HTTP callouts in LWC. Import the fetch
method and use it to send requests to external services.
8. What is the use of the @track
decorator in LWC?
The @track
decorator is used to track changes to properties so that the component can rerender when those properties change.
9. How do you handle errors in Lightning Web Components?
You can use the try
–catch
block to catch errors and handle them gracefully. Additionally, you can display error messages to users.
10. What is the difference between lightning-card
and lightning-layout
components in LWC? lightning-card
provides a styled container for content, while lightning-layout
is used for creating layouts with multiple regions.
11. Explain the concept of shadow DOM in LWC.
Shadow DOM is a web standard that encapsulates a component’s styles and structure, preventing CSS conflicts with other components on the page.
12. What is the role of the wire
service in LWC?
The wire
service is a module that provides reactive data binding, allowing you to get and update data from a data source without needing to write boilerplate code.
13. How do you handle user interactions in LWC?
You can use event handlers in the template to listen to user interactions, such as clicks or inputs, and call methods in the component’s JavaScript.
14. What is the purpose of the api
property in LWC?
The api
property allows you to expose properties and methods in a Lightning Web Component that can be used by parent components or by external code.
15. What is the difference between imperative and reactive Apex methods in LWC?
Imperative methods use @wire
to fetch data when needed, while reactive methods use the @wire
service to automatically update data when it changes.
16. How can you make a Lightning Web Component available for use in the Salesforce App Builder? You need to define a custom component in the meta.xml
file of your LWC and set the isExposed
attribute to true
.
17. What is the purpose of the lightning-record-edit-form
component in LWC?
lightning-record-edit-form
is used to create, view, or edit a record’s fields using the Salesforce Lightning Data Service.
18. How can you communicate between sibling components in LWC?
You can use custom events and properties defined in a common parent component to facilitate communication between sibling components.
19. What is the role of the lightning/navigation
module in LWC?
The lightning/navigation
module allows you to navigate users to different pages within Salesforce, such as records, lists, or custom pages.
20. How do you unit test a Lightning Web Component?
You can write unit tests for LWC using Jest framework, which is supported by Salesforce. Test components, properties, and methods using Jest functions.