Overview
Creating a new Lightning Web Component (LWC) from scratch is a foundational skill for Salesforce developers. LWC allows developers to create reusable, encapsulated components that can be used in Salesforce Lightning pages and apps. Understanding how to create, structure, and deploy LWC components is crucial for developing efficient, scalable, and maintainable Salesforce applications.
Key Concepts
- Component Structure: Understanding the files that make up an LWC component.
- Component Configuration: Knowledge of how to configure a component's metadata.
- Component Communication: Grasping the methods for component interaction, including events and public properties.
Common Interview Questions
Basic Level
- What are the basic files required to create an LWC component?
- How do you create a new LWC component in Salesforce DX?
Intermediate Level
- How can you make a property in an LWC component reactive?
Advanced Level
- How do you handle communication between nested LWC components?
Detailed Answers
1. What are the basic files required to create an LWC component?
Answer: To create a basic LWC component, at least three files are required: HTML, JavaScript, and XML metadata. The HTML file defines the component's structure, the JavaScript file contains the component's functionality, and the XML file provides the component's configuration.
Key Points:
- HTML File: Describes the component's UI structure.
- JavaScript File: Contains the logic and manages the component's behavior.
- XML File: Holds metadata for the component, such as its API version and whether it's accessible in the Salesforce app.
Example:
// Unfortunately, LWC components aren't developed with C#, so providing a C# example isn't applicable. LWC utilizes HTML, JavaScript, and XML.
2. How do you create a new LWC component in Salesforce DX?
Answer: In Salesforce DX, you can create a new LWC component using the Salesforce CLI. Use the force:lightning:component:create command along with specifying the component name and the directory where the component should be created.
Key Points:
- Use Salesforce CLI to streamline development.
- Specify the component name and target directory.
- Each component is created with default files.
Example:
// Not applicable, as Salesforce CLI commands are not C# code. Here's a CLI command example instead:
// sfdx force:lightning:component:create --componentname myNewComponent --outputdir lwc
3. How can you make a property in an LWC component reactive?
Answer: To make a property reactive in LWC, you use the @track decorator. This tells the framework to monitor changes to the property and re-render the component whenever its value changes.
Key Points:
- @track is used for objects and arrays.
- Primitive data types (string, number, boolean) are reactive by default.
- Reactivity triggers UI updates automatically.
Example:
// LWC syntax differs from C#, focusing on JavaScript. Here's a JavaScript example:
// @track myProperty;
4. How do you handle communication between nested LWC components?
Answer: Communication between nested LWC components can be managed through a combination of public properties, events, and API methods. Child components can send data to parent components using custom events, while parent components can pass data down to child components via public properties.
Key Points:
- Public Properties: Use @api decorator to expose properties to parent components.
- Custom Events: Use CustomEvent to dispatch events from child to parent.
- API Methods: Expose methods in child components using @api for parent components to invoke.
Example:
// LWC is based on JavaScript, so C# code examples are not directly applicable. Below is a conceptual JavaScript snippet:
// Child component dispatching an event to the parent:
this.dispatchEvent(new CustomEvent('myevent', { detail: { key: 'value' } }));
This guide covers the basics of creating and managing LWC components, focusing on structure, configuration, and communication.
