Tuesday, September 26, 2017

Salesforce lightning Interview Question and Answers

What is Salesforce Lightning?
  • Lightning is the umbrella term for the collection of tools and technologies e.g. Lightning component framework, lightning experience, lightning app builder etc.
  • Lightning  became available in October 2015 with the release of Winter ‘16

What are Lightning components?
  • Components are the self contained source and reusable units of an app.
  • UI Framework - Built on Open Aura Framework.
  • It is used for developing web apps - For mobile and desktop devices.
  • It is a client server framework.
  • It helps to accelerate the development.
  • It helps to improve application peformance. It has stateful client and stateless server.
  • It has several reusable out of the box components.
  • A Component can contain other components, JS, HTML and CSS.
  • Encapsulated, configured through attributes and communicate through events.
  • LC are device aware and have cross browser compatibility.

What is Aura? What is the relation of Aura with Salesforce Lightning?
  • It is a UI Framework for developing dynamic web apps for mobile and desktop devices.
  • It is totally independent of Salesforce.
  • It has several out of the box components like button,checkbox,datagrid etc.
  • It is available at https://github.com/forcedotcom/aura
  • The aura namespace contains components to simplify your app logic, and the ui namespace contains components for user interface elements like buttons and input fields.
  • The Lightning Component framework is built on the open source Aura framework.


What is Lightning Experience
  • Lightning Experience is the new, modern user experience and interface for using Salesforce.
  • It has a modern and responsive design. It is optimized for users so that they can work very fast and easily on records so that they are more productive.
  • Not every feature of Salesforce is supported in Lightning Experience yet. Because of this, Salesforce Classic – is still available, and users can switch between Lightning Experience and Salesforce Classic with ease.
  • It is not necessary for the entire org to move to Lightning Experience at the same time. Certain users can enable Lightning Experience, while others can continue using Salesforce Classic.
  • Admins can enable Lightning Experience access at the user, profile, and organization level.

What are Lightning Apps?

Lightning Apps are made of Lightning components.
  • Lightning App  is a special top-level component whose markup is in a .app resource.
  • You can Access app using url of this pattern https://.lightning.force.com//.app
  • Mark up starts with
  • Types
    • Standalone – can be hosted outside SF1 and LE, like lightning out and VF pages
    • Lightning Experience and SF1 – Can take advantage of record create and edit pages, among other benefits

What is pre-requisite for learning Lightning component development?
  • Learn JavaScript. You must have intermediate level of JavaScript knowledge.
  • Learn concept of web components like google polymer, react,etc
  • Learn Single page app concept.
  • CSS3 Knowledge.
  • JavaScript debugging.
  • Apex knowledge for server side logic coding.

What is a Lightning Component Bundle? OR What is a Lightning component made up of?

A component bundle contains a component or an app and all its related resources.
  • CSS Styles
  • Controller
  • Design
  • Documentation
  • Renderer
  • Helper
  • SVG File

What are the types of events in Lightning?
  • Component events are handled by the 
    • component itself or 
    • a component that instantiates or contains the component.
  • Application events are handled by 
    • all components that are listening to the event. These events are essentially a traditional publish-subscribe model.

What is @AuraEnabled annotation used for?
  • The @AuraEnabled annotation enables client side access to an Apex controller method.
  • Providing this annotation makes your methods available to your Lightning components.
  • Only methods with this annotation are exposed. 

What is Lightning Design System (SLDS)?
  • The Salesforce Lightning Design System includes the resources to create user interfaces consistent with the Salesforce Lightning principles, design language, and best practices. 
  • It helps to create an intuitive UI with less number of clicks which is modern and beautiful.

What is the use of access=“global”?
  • Mark your resources, such as a component, with access="global" to make the resource usable outside of your own org. For example, if you want a component to be usable in an installed package or by a Lightning App Builder user or a Community Builder user in another org.

What are Component Attributes?
  • Component attributes are like member variables on a class in Apex.
  • They are typed fields that are set on a specific instance of a component, and can be referenced from within the component's markup using an expression syntax. 
  • Attributes enable you to make components more dynamic.
  • Use the tag to add an attribute to the component or app.
  • All attributes have a name and a type.
  • Attributes may be marked as required by specifying required="true", and may also specify a default value.
  
What is Lightning Data Services?
  • It is data Layer for Lightning
  • Can be equated to Standard Controllers in Visualforce
  • Use Lightning Data Service to load, create, edit, or delete a record in your component without requiring Apex code.
  • No SOQL required.
  • Lightning Data Service handles sharing rules and field-level security automatically.
  • Declarative CRUD operations
  • Auto notify on record changes
  • Offline Access for Salesforce1
  • Lightning Data Service improves performance and user interface consistency.

What is Salesforce Lightning CLI?
  • It is part of  Salesforce DX CLI Command that lets you scan your code for general JavaScript coding issues and Lightning-specific issues.
  • Useful for preparing your Lightning components code for LockerService enablement.
  • Based on ESLint project.

Is Namespace required for lightning component creation?
  • If you’re not creating managed packages for distribution then registering a namespace prefix isn’t required, but it’s a best practice for all but the smallest organisations.


What are Local and Global ids with respect to lightning component?
  • A component has two types of IDs: a local ID and a global ID. 
  • You can retrieve a component using its local ID in your JavaScript code. 
  • A global ID can be useful to differentiate between multiple instances of a component or for debugging purposes.
  • Local ID is created by using the aura:id attribute.
  • example
  • To find the local ID for a component in JavaScript, use cmp.getLocalId()
  • Every component has a unique globalId, which is the generated runtime-unique ID of the component instance.
  • A global ID  is not guaranteed to be the same beyond the lifetime of a component, so it should never be relied on.

What is the requirement for a component to be used in a custom tab in lightning experience or Salesforce1?

  • Add the force:appHostable interface to a Lightning component to allow it to be used as a custom tab in Lightning Experience or Salesforce1.
  • Components that implement this interface can be used to create tabs in both Lightning Experience and Salesforce1.

What is FlexiPage?
  • FlexiPage Represents the metadata associated with a Lightning page. 
  • A Lightning page represents a customizable screen made up of regions containing Lightning components.


Watch it in video format https://goo.gl/zDTPt4

1 comment:

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