LWC Interview Questions and Answers – Part 2

Q: How do you import multiple modules in LWC?

A: You import multiple modules using the ES6 import syntax, e.g., import { LightningElement, api, track } from 'lwc';.

Q: What is a wire adapter in LWC?

A: A wire adapter is a built-in mechanism to connect a property or method to Salesforce data using the @wire decorator.

Q: How do you bind attributes to HTML elements in LWC?

A: You bind attributes to HTML elements using template syntax, e.g., <input value={myValue} />.

Q: How do you create a custom event in LWC?

A: You create a custom event using the CustomEvent constructor and dispatch it with this.dispatchEvent.

Q: What is the purpose of the import { ShowToastEvent } from 'lightning/platformShowToastEvent'; statement?

A: It imports the ShowToastEvent class used to display toast notifications in LWC.

Q: How do you use the lightning-input component in LWC?

A: You use it by including the lightning-input tag in your HTML template, e.g., <lightning-input label="Name" value={name}></lightning-input>.

Q: What is the track decorator replaced with in LWC?

A: The track decorator is no longer needed; reactive properties are now handled natively by LWC.

Q: How do you use the lightning-datatable component?

A: You use it by defining columns and data in your JavaScript file and including the lightning-datatable tag in your HTML template.

Q: What is the this.template.querySelector method used for in LWC?

A: It is used to select a DOM element within the component’s template.

Q: How do you use slots in LWC?

A: Slots are used to create placeholder areas in a component that can be filled with markup passed from the parent component using the <slot> element.

Q: How do you dynamically load a module in LWC?

A: You dynamically load a module using the import() function, which returns a promise.

Q: How do you perform imperative Apex calls in LWC?

A: You perform imperative Apex calls by importing the Apex method and using it within a JavaScript function.

Q: How do you debug LWC components?

A: You debug LWC components using browser developer tools, adding breakpoints in your JavaScript code, and using console.log.

Q: What is the purpose of the .xml file in an LWC component?

A: The .xml file defines the metadata for the component, including where it can be used within Salesforce.

Q: How do you handle form submission in LWC?

A: You handle form submission by adding an event listener for the submit event and defining the handling logic in JavaScript.

Q: What is the lightning-record-edit-form component?

A: The lightning-record-edit-form component is a built-in LWC component that provides a form for editing a record.

Q: How do you reference a child component in LWC?

A: You reference a child component using the @api decorator to expose properties or methods.

Q: How do you cache data in LWC?

A: You cache data using the @wire service with the cacheable parameter or by storing data in a JavaScript variable.

Q: How do you define a getter in LWC?

A: You define a getter in LWC using the get keyword in your JavaScript class.

Q: What is the connectedCallback lifecycle hook used for?

A: It is used to execute code when the component is inserted into the DOM.

Q: How do you handle promise rejection in LWC?

A: You handle promise rejection using .catch() on the promise or try-catch blocks with async/await.

Q: How do you import static resources for images in LWC?

A: You import static resources for images using the @salesforce/resourceUrl scoped module and referencing them in your template.

Q: How do you add keyboard event listeners in LWC?

A: You add keyboard event listeners using addEventListener in the JavaScript file, e.g., this.template.addEventListener('keydown', this.handleKeyDown);.

Q: What is the lwc:dom="manual" directive used for?

A: The lwc:dom="manual" directive allows you to manually control the DOM inside a template.

Q: How do you create a custom Lightning icon?

A: You create a custom Lightning icon by using the lightning-icon component and specifying the icon attributes.

Q: How do you implement a search feature in LWC?

A: You implement a search feature by capturing user input, querying data using Apex, and displaying the results dynamically.

Q: How do you format dates in LWC?

A: You format dates using JavaScript’s Intl.DateTimeFormat or utility libraries like moment.js.

Q: What is the purpose of this.template.querySelectorAll in LWC?

A: It is used to select multiple DOM elements within the component’s template.

Q: How do you create a reactive wire property in LWC?

A: You create a reactive wire property by decorating a property with @wire and using it in the template.

Q: How do you create a dynamic table in LWC?

A: You create a dynamic table by defining columns and data in your JavaScript file and using the lightning-datatable component in your template.

LWC Interview Questions and Answers

LWC Interview Questions and Answers – Part 1

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