A GradX Academy student with 3 years of experience recently appeared for an LTI Mindtree interview for a Salesforce LWC Developer role in January 2025. Below are the questions asked along with detailed answers to help you in your interview preparation.

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1️⃣ What is LWC, and how is it different from Aura Components?

LWC (Lightning Web Components) is a modern framework built on Web Standards to develop UI components in Salesforce. It replaces Aura Components by leveraging native JavaScript, HTML, and CSS for better performance and reduced framework overhead.

Differences:

Feature	LWC	Aura Components
Framework	Uses Web Standards (JavaScript, HTML, CSS)	Uses Salesforce Aura Framework
Performance	Faster & lightweight (runs natively in the browser)	Slower due to framework overhead
Data Binding	Uses Reactive Properties	Uses @track (before Winter ’21)
Component Communication	Custom Events & LMS	Application Events, Component Events
DOM	Shadow DOM support	Uses Locker Service

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2️⃣ Can you explain the LWC component lifecycle hooks?

LWC provides lifecycle hooks that trigger during component initialization, rendering, and destruction.

Hook	Description
constructor()	Initializes the component (Avoid using this for reactive properties).
connectedCallback()	Executes when the component is inserted into the DOM (best for fetching data).
renderedCallback()	Executes when the component is rendered (avoid infinite loops).
disconnectedCallback()	Executes when the component is removed from the DOM.
errorCallback(error, stack)	Handles errors in the component.

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3️⃣ How does reactivity work in LWC?

Reactivity in LWC is achieved using JavaScript Proxy Objects.

• Reactive properties automatically update the UI when their values change.
• Decorators like @api, @track, and @wire manage reactivity.
• Example:

import { LightningElement, track } from 'lwc';
export default class Example extends LightningElement {
    @track message = 'Hello'; // Reactive property
    handleChange(event) {
        this.message = event.target.value; // UI updates automatically
    }
}

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4️⃣ What are decorators in LWC? Explain @api, @track, and @wire.

Decorators in LWC enhance class properties with special behavior.

Decorator	Use Case
@api	Marks a property as public, accessible from parent components.
@track	Tracks changes in primitive data types (obsolete in newer versions).
@wire	Fetches data from Apex or Salesforce Data APIs reactively.

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5️⃣ How do you call an Apex method from LWC?

Apex methods are called in LWC using imperative or wired methods.

1️⃣ Imperative Call (On-Demand)

import { LightningElement, track } from 'lwc';
import getAccounts from '@salesforce/apex/AccountController.getAccounts';

export default class AccountList extends LightningElement {
    @track accounts = [];

    handleLoad() {
        getAccounts()
            .then(result => { this.accounts = result; })
            .catch(error => { console.error(error); });
    }
}

2️⃣ Wire Adapter (Reactive)

import { LightningElement, wire } from 'lwc';
import getAccounts from '@salesforce/apex/AccountController.getAccounts';

export default class AccountList extends LightningElement {
    @wire(getAccounts) accounts;
}

6️⃣ What is the difference between @AuraEnabled(cacheable=true) and @AuraEnabled(cacheable=false)?

Attribute	Description
cacheable=true	Optimized for read operations (querying records), data is cached in Lightning Data Service.
cacheable=false	Used for DML operations (insert, update, delete), no caching.

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7️⃣ How do you pass data between parent and child components?

LWC supports parent-child communication using @api, Custom Events, and LMS.

1️⃣ Parent-to-Child (@api)

// Parent Component
<template>
    <c-child message="Hello from Parent"></c-child>
</template>

// Child Component
import { LightningElement, api } from 'lwc';
export default class Child extends LightningElement {
    @api message; // Receiving data from parent
}

2️⃣ Child-to-Parent (Custom Event)

// Child Component
import { LightningElement } from 'lwc';
export default class Child extends LightningElement {
    sendData() {
        this.dispatchEvent(new CustomEvent('childmessage', { detail: 'Hello Parent' }));
    }
}

// Parent Component
<template>
    <c-child onchildmessage={handleMessage}></c-child>
</template>

// Parent JS
handleMessage(event) {
    console.log(event.detail); // Output: Hello Parent
}

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8️⃣ How do you optimize the performance of an LWC component?

🔹 Use cacheable=true in Apex for data caching.
🔹 Minimize DOM manipulations by using lightning-datatable.
🔹 Use LDS (Lightning Data Service) instead of Apex for CRUD operations.
🔹 Debounce API calls to prevent unnecessary executions.

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9️⃣ Hands-On Coding Question: Fetch and Display Accounts in a Datatable

Apex Controller (AccountController.cls)

public with sharing class AccountController {
@AuraEnabled(cacheable=true)
public static List getAccounts() {
return [SELECT Id, Name, Industry FROM Account LIMIT 10];
}
}

LWC Component (accountTable.js)

import { LightningElement, wire } from 'lwc';
import getAccounts from '@salesforce/apex/AccountController.getAccounts';

export default class AccountTable extends LightningElement {
    @wire(getAccounts) accounts;
}

LWC HTML (accountTable.html)

<template>
    <lightning-datatable
        key-field="Id"
        data={accounts.data}
        columns={columns}>
    </lightning-datatable>
</template>

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🔥 Final Tips for Cracking the Interview

✅ Master JavaScript ES6+ (Promises, Async/Await, Spread Operator).
✅ Understand Apex & SOQL optimizations to improve performance.
✅ Be prepared for hands-on coding questions in LWC.
✅ Practice real-world scenarios like parent-child communication, datatables, and pagination.

If you’re preparing for Salesforce LWC interviews, these answers will give you a strong foundation.

💬 Have you faced similar LWC interview questions? Drop your thoughts in the comments! ⬇️

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