Interview Questions

1. What are Lightning Web Components (LWC)?

2. What is the file structure of Lightning Web Components?

• myComponent folder
• myComponent.html
• myComponent.js
• myComponent.js-meta.xml
• myComponent.css
• myComponent.svg

3. How can you display components HTML conditionally

With the help of if:true|false directive

4. How we can iterate list in Lightning Web Component (LWC)

With the help of for:each and Iterator directive

5. Can we render multiple templates based on condition?

Yes we can render multiple templates based on the render method.

Temp1.html

<template>
    <p>
        hello Temp-1,
    </p>
    <p>
        this is the template One
    </p>
	<button onclick={handleToggleButton}>Change</button>
</template>

Temp2.html

<template>
    <p>
        hello Temp2,
    </p>
    <p>
        this is the template Two
    </p>
    <button onclick={handleToggleButton}>Change</button>
</template>

import { LightningElement, track } from 'lwc';
import {default as mainTemplate} from './Temp1.html'
import {default as anotherTemplate} from './Temp2.html'

export default class Salesforcedriller extends LightningElement {

    @track usetemp = false;

    render() {
        return this.usetemp ? mainTemplate : anotherTemplate;
    }

    handleToggleButtonPress() {
        this.usetemp = !this.usetemp;
    }
}

6. What are the public properties in Lightning Web Components?

@api is the public reactive property.

7. What are the types of decorators in lightning web components?

We have 3 Decorators in Lightning Web Components.

1. @api
2. @track
3. @wire

8. How many files are created by default when we create a Lightning Web Component?

Three files are created as below.

1. HTML file.
2. JavaScript file.
3. Meta configuration file.

9. Can components share the style sheet?

No.

10. How to pass data from child to parent?

With the help of custom events.
this.dispatchEvent(new CustomEvent(EventName));

11. Can we use aura and LWC simultaneously?

Aura can include LWC but LWC can not include Aura.

12. Best practices for lightning?

• Do not use so many Console.log
• Try to use LDS As much as possible
• limit number of event handlers in your Lightning component
• Caching the data at the client side.
• Don’t return a huge number of rows at once from backend
• Try to use limits in the query result.
• Try to minimize the column on the result set.
• Use @AuraEnabled(cacheable=true) to reduce the server call.

13. Is there any limit on how many components to have in one Application ?

There is no limit.

14. What is the template?

It is a reusable structure in the HTML page.

15. Which parts of Lightning Components are server-side and which are client-side ?

JavaScript on the client side and Apex on the server side.