Real Scenario-Based Questions on Lightning Web Components (LWC)

In the dynamic world of Salesforce development, mastering Lightning Web Components (LWC) is essential for creating efficient and responsive user interfaces. As businesses increasingly rely on Salesforce to streamline their processes, developers with expertise in LWC are in high demand. To prepare for the challenges that come with real-world projects and interviews, it’s crucial to have a solid grasp of LWC’s capabilities in practical scenarios.

Asking simple straightforward questions in Lightning Web Components (LWC) is history. Few years back Salesforce certified people were very less. Hence criteria was just to check whether that person know about basic Lightning Web Component (LWC) or not.

So questions used to be:
• How is LWC different from Aura?
• What is Lightning Web Components (LWC)?
• How is LWC different from Aura?
• How do LWC components differ from Aura components?
• What is Data Binding?
• What is the use of the Salesforce Lightning Design System?
etc.

If you notice above questions are crisp to the point. But now since in market there are many Salesforce certified people above style of interview doesn’t work. One could easily memories these.

I too take interviews in my company and now style is different. Focus is more to ask scenario questions rather then what how etc.

This blog delves into a comprehensive collection of `real scenario-based questions on Lightning Web Components`, offering valuable insights and hands-on examples. These questions are designed to simulate real-world situations that developers often encounter during application development, making them an excellent resource for both beginners and experienced developers looking to enhance their skills.

Each scenario is tailored to focus on specific aspects of LWC development, ranging from the basics to more advanced topics. The questions touch upon various areas, including:

1. Component Communication and Interaction: Learn how to effectively communicate between components using properties and events, utilizing event bubbling and composing to share data seamlessly.

2. Integration with External Libraries: Explore the world of third-party JavaScript libraries and how to integrate them smoothly into your LWC components using the “loadScript” utility.

3. Dynamic Styling and Responsive Design: Discover how to apply dynamic styles and create responsive designs that adapt to different screen sizes based on user input.

4. Data Management and Apex Integration: Understand data management within LWC by utilizing reactive properties and the “wire” service. Learn how to interact with Apex classes to fetch and manipulate Salesforce data.

5. Interactive UI Elements: Implement custom notifications and create interactive charts, searchable components, and multi-step wizards to enhance user interaction.

6. Real-Time Updates and Location Services: Build components that harness real-time updates through Lightning Message Service and utilize browser geolocation APIs to display user coordinates.

MIND IT !

Each scenario is accompanied by example code that demonstrates how to tackle the challenges presented. By practicing these real scenario-based questions, developers can gain a deeper understanding of LWC’s functionalities and become better equipped to handle diverse development scenarios.

In a nutshell, this blog offers a user-friendly exploration of real scenario-based questions that shed light on the various dimensions of Lightning Web Components. Whether you’re preparing for interviews or aiming to boost your LWC skills, these real-world scenarios and solutions provide a solid framework for becoming a proficient LWC developer.

LWC Scenario 1 : Dynamic Form Creation
Question: You need to create a dynamic form with input fields that change based on user selection. How would you implement this in LWC?

Answer: Implementing a dynamic form with input fields that adapt based on user selection in Lightning Web Components (LWC) involves a combination of conditional rendering and event handling. Here’s how you could approach it:

Step 1: Define the Component

Create a Lightning Web Component to house the dynamic form. Let’s call it `DynamicForm`.

Step 2: Define the Form Fields

In the `DynamicForm` component, define the possible input fields that can be displayed based on user selection. For example, you can include fields for name, email, phone number, and address.

<!-- HTML File - dynamicForm.html -->
<template>
    <lightning-combobox label="Select Form Type" value={selectedFormType} options={formTypeOptions} onchange={handleFormTypeChange}></lightning-combobox>
     
    <template if:true={showNameField}>
        <lightning-input label="Name"></lightning-input>
    </template>
     
    <template if:true={showEmailField}>
        <lightning-input label="Email"></lightning-input>
    </template>
     
    <!-- Add similar templates for other fields -->
</template>

Step 3: Handle User Selection

Create methods in the `DynamicForm` component’s JavaScript file to handle user selections and toggle the visibility of input fields accordingly.

// JS File - dynamicForm.js
import { LightningElement, track } from 'lwc';
 
export default class DynamicForm extends LightningElement {
    @track selectedFormType = '';
    @track showNameField = false;
    @track showEmailField = false;
    // Add similar tracking variables for other fields
 
    formTypeOptions = [
        { label: 'Select Form Type', value: '' },
        { label: 'Name', value: 'name' },
        { label: 'Email', value: 'email' },
        // Add options for other fields
    ];
 
    handleFormTypeChange(event) {
        this.selectedFormType = event.detail.value;
        this.showNameField = this.selectedFormType === 'name';
        this.showEmailField = this.selectedFormType === 'email';
        // Update similar variables for other fields
    }
}

Step 4: Display the Dynamic Form

Include the `DynamicForm` component in a parent component or app where the user can interact with it.

<template>
    <c-dynamic-form></c-dynamic-form>
</template>

Output:

In this setup, the user can choose a form type from a dropdown, and the corresponding input fields will dynamically appear based on their selection. This approach allows you to create flexible and adaptive forms in LWC that respond to user preferences.

LWC Scenario 2 : Data Fetch and Display
Question: You want to fetch and display a list of account records using the “wire” service. How do you achieve this in LWC?

Answer: To fetch and display a list of account records using the “wire” service in Lightning Web Components (LWC), you can use the `wire` decorator along with the `getRecord` or `getListUi` adapter. Here’s how you can achieve this:

Step 1: Define the Component.

Create a Lightning Web Component to display the list of account records. Let’s call it `AccountList`.

Step 2: Fetch and Display Account Records

In the `AccountList` component’s JavaScript file, use the `wire` decorator to fetch the account records using the `getListUi` adapter. The `getListUi` adapter allows you to retrieve a list of records and their associated data. Here’s how you can do it:

// JS File - accountList.js
import { LightningElement, wire } from 'lwc';
import { getListUi } from 'lightning/uiListApi';
import ACCOUNT_OBJECT from '@salesforce/schema/Account';
 
export default class AccountList extends LightningElement {
    @wire(getListUi, { objectApiName: ACCOUNT_OBJECT, listViewApiName: 'AllAccounts' })
    accounts;
 
    get accountList() {
        return this.accounts.data ? this.accounts.data.records.records : [];
    }
}

In this example, the `getListUi` adapter is used to fetch account records from the standard “AllAccounts” list view. The `accounts` property is automatically populated with the retrieved data.

Step 3: Display Account Records

In the `AccountList` component’s HTML file, use iteration to display the fetched account records:

<!-- HTML File - accountList.html -->
<template>
    <lightning-card title="Account List">
        <template if:true="{accountList}">
            <ul>
                <template for:each="{accountList}" for:item="account">
                    <li key="{account.id}">{account.fields.Name.value}</li>
                </template>
            </ul>
        </template>
    </lightning-card>
</template>

In this example, the fetched account records are iterated over and displayed in a list format.

Output:

By following these steps, you’re effectively using the “wire” service with the getListUi adapter to fetch and display a list of account records in a Lightning Web Component.

LWC Scenario 3 : Dynamic Form Creation
Question: When a user submits a record, handle any errors and provide feedback using toasts.

Answer:

HTML (submitRecord.html):

<!-- HTML File - submitRecord.html -->
<template>
    <lightning-card title="Submit Record">
        <div class="slds-p-horizontal_small">
            <lightning-input label="Name" value={recordName} onchange={handleNameChange}></lightning-input>
            <lightning-button label="Submit" onclick={handleSubmit}></lightning-button>
        </div>
    </lightning-card>
</template>

JavaScript (submitRecord.js):

// JS File - submitRecord.js
import { LightningElement, track } from 'lwc';
import { ShowToastEvent } from 'lightning/platformShowToastEvent';
 
export default class SubmitRecord extends LightningElement {
    @track recordName = '';
 
    handleNameChange(event) {
        this.recordName = event.target.value;
    }
 
    handleSubmit() {
        if (this.recordName) {
            // Simulate record submission and handle success
            this.handleSuccess();
        } else {
            // Handle error and show toast
            this.handleError('Please enter a valid name.');
        }
    }
 
    handleSuccess() {
        // Handle successful submission and show success toast
        const event = new ShowToastEvent({
            title: 'Success',
            message: 'Record submitted successfully.',
            variant: 'success',
        });
        this.dispatchEvent(event);
    }
 
    handleError(errorMessage) {
        // Handle error and show error toast
        const event = new ShowToastEvent({
            title: 'Error',
            message: errorMessage,
            variant: 'error',
        });
        this.dispatchEvent(event);
    }
}

In this example, when a user enters a name and clicks the “Submit” button, the `handleSubmit` method checks if a valid name is provided. If a valid name is entered, the `handleSuccess` method is called to show a success toast using the `lightning/platformShowToastEvent` module. If no name is provided, the `handleError` method is called to show an error toast.

Output:

showSuccessToast : If a valid name is entered, the `handleSuccess` method is called to show a success toast.

showErrorToast: If no name is provided, the `handleError` method is called to show an error toast.

The `lightning/platformShowToastEvent` module provides an easy way to display toast notifications in Lightning Web Components. You can customize the appearance and behavior of the toast using the properties of the `ShowToastEvent` object.

MIND IT !

Remember to include the necessary Lightning Design System styles in your component for proper styling. You can also enhance this example by integrating it with actual record submission logic and handling more complex scenarios.

LWC Scenario 4 : Component Communication
Question: You need to create a dynamic form with input fields that change based on user selection. How would you implement this in LWC?

Answer: Implementing communication between two sibling components via a shared parent component is a common requirement in Lightning Web Components (LWC). This approach allows you to pass data or trigger actions between components that are not directly connected. Here’s how you can achieve this:

Step 1: Create the Parent Component

Create a parent component that will serve as the mediator between the two sibling components. Let’s call it ParentComponent.

Step 2: Define Sibling Components

Create two sibling components that need to communicate with each other. Let’s call them `SiblingComponentA` and `SiblingComponentB`.

Step 3: Communication Flow

Here’s how the communication will flow:

1. `SiblingComponentA` will send data to the `ParentComponent`.
2. The `ParentComponent` will receive the data and pass it to `SiblingComponentB`.

Step 4: Define the Parent Component

In the HTML file of `ParentComponent`, include the two sibling components and define a method to receive and pass data.

<!-- ParentComponent.html -->
<template>
    <c-sibling-component-a ondatachange="{handleDataChange}"></c-sibling-component-a>
    <c-sibling-component-b data="{sharedData}"></c-sibling-component-b>
</template>

In the JavaScript file of `ParentComponent`, define the method to handle data changes and pass the data between the sibling components.

// ParentComponent.js
import { LightningElement, track } from 'lwc';
 
export default class ParentComponent extends LightningElement {
    @track sharedData = '';
 
    handleDataChange(event) {
        this.sharedData = event.detail;
    }
}

Step 5: Define Sibling Component A

In the HTML file of `SiblingComponentA`, create an input field to update the shared data and dispatch a custom event to notify the parent component.

<!-- SiblingComponentA.html -->
<template>
    <input type="text" value="{localData}" onchange="{handleInputChange}">
</template>

In the JavaScript file of `SiblingComponentA`, define the method to handle input changes and dispatch a custom event to notify the parent component.

// SiblingComponentA.js
import { LightningElement } from 'lwc';
 
export default class SiblingComponentA extends LightningElement {
    localData = '';
 
    handleInputChange(event) {
        this.localData = event.target.value;
        const dataChangeEvent = new CustomEvent('datachange', { detail: this.localData });
        this.dispatchEvent(dataChangeEvent);
    }
}

Step 6: Define Sibling Component B

In the HTML file of `SiblingComponentB`, display the shared data received from the parent component.

<!-- SiblingComponentB.html -->
<template>
    <p>Shared Data: {data}</p>
</template>

In the JavaScript file of `SiblingComponentB`, define a property to receive the shared data from the parent component.

// SiblingComponentB.js
import { LightningElement, api } from 'lwc';
 
export default class SiblingComponentB extends LightningElement {
    @api data;
}

By following these steps, you’ll establish communication between two sibling components via a shared parent component. SiblingComponentA sends data to the ParentComponent, and then the ParentComponent passes that data to SiblingComponentB, allowing the two siblings to communicate effectively.

LWC Scenario 5 : Third-Party Library Integration
Question: Integrate the “Chart.js” library to create a bar chart in a Lightning Web Component.

Answer: ”Chart.js” is a popular JavaScript library for creating interactive charts. We’ll create an LWC that displays a bar chart using sample data.

Step 1: Create a New Lightning Web Component

Create a Lightning Web Component to display the Chart Bar. Let’s call it `ChartComponent`.

<!-- HTML File - chartComponent.html -->
<template>
  <lightning-card title="Sample Chart">
    <div>
      <canvas class="donut" lwc:dom="manual"></canvas>
    </div>
  </lightning-card>
</template>

Step 2: Add the “Chart.js” Library to Static Resources

1. Download the “Chart.js” library from the official website: https://www.chartjs.org/
2. Create a static resource in Salesforce with the downloaded “Chart.js” library files.

Step 3: Include the “Chart.js” Library in the Component

In the JavaScript file (chartComponent.js) of your component, import the “Chart.js” library from the static resource and create the bar chart:

// JS File - chartComponent.js
import { LightningElement } from 'lwc';
import { loadScript, loadStyle } from 'lightning/platformResourceLoader';
import CHARTJS from '@salesforce/resourceUrl/ChartJs';
import { ShowToastEvent } from 'lightning/platformShowToastEvent';
 
export default class ChartComponent extends LightningElement {
    chartJsInitialized = false;
 
    renderedCallback() {
        if (this.chartJsInitialized) {
            return;
        }
        this.chartJsInitialized = true;
 
        loadScript(this, CHARTJS)
            .then(() => {
                this.initializeChart();
            })
            .catch(error => {
                this.dispatchEvent(new ShowToastEvent({
                    title: 'Error',
                    message: 'Error loading Chart.js library',
                    variant: 'error'
                }));
            });
    }
 
    initializeChart() {
        const ctx = this.template.querySelector('canvas.donut').getContext('2d');
        new window.Chart(ctx, {
            type: 'bar',
            data: {
                labels: ['January', 'February', 'March', 'April', 'May'],
                datasets: [{
                    label: 'Sales',
                    data: [50, 30, 60, 40, 70],
                    backgroundColor: 'rgba(75, 192, 192, 0.2)',
                    borderColor: 'rgba(75, 192, 192, 1)',
                    borderWidth: 1
                }]
            },
            options: {
                scales: {
                    y: {
                        beginAtZero: true
                    }
                }
            }
        });
    }
}

In this example, we integrated the “Chart.js” library into an LWC named `ChartComponent` using the `loadScript` and `loadStyle` methods. The JavaScript file loads the “Chart.js” library from a static resource and initializes the bar chart using the `renderedCallback` lifecycle hook. By avoiding the CDN, you have more control over the library’s version and can comply with security requirements.

Output:

Customize the static resource names and paths based on your setup. This approach allows you to seamlessly integrate “Chart.js” or other third-party libraries into your Lightning Web Components while managing the resources within your Salesforce environment.

For More Questions visit the link below:

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Thanks for reading ☺️