Salesforce LWC Interview Questions Part - 6

 LWC Lifecycle Hooks

A lifecycle hook is a callback method triggered at a specific phase of a component.

Image source: 

61. What is the use of the constructor method in LWC?

constructor method gets called when the component instance is created. This method also flows from parent to child, which means that it fires in the parent first. You can’t access child elements because they don’t exist yet. Properties are assigned to the component after construction and before the connectedCallback() method execute.  

62. What is the use of the connectedCallback() method in LWC?

connectedCallback method is called when the element is inserted into a document. This method flows from parent to child. You can’t access child elements because they don’t exist yet. connectedCallback is used with the initial properties passed to the component, fetch data, set up caches, or listen for events.
The connectedCallback() can fire more miltiple times.If you remove an element and then insert it into another position, such as when you reorder a list, the connectedCallback fires several times.

63. What is the use of the renderedCallback method in LWC?

The renderedCallback() is Use to perform logic after a component has finished the rendering phase. This hook flows from child to parent.

64. What is the use of the render method in LWC?

It's used to display the element in UI. It may be called before or after connectedCallback(). The main use purpose is to conditionally render a template. Define business logic to decide which template (HTML file) to use. The method must return a valid HTML template. 

65. What is the use of the disconnectedCallback method in LWC?

disconnectedCallback method get's called when the element is removed from a document. disconnectedCallback  hook flows from parent to child. Use disconnectedCallback() method to clean up work done in the connectedCallback() method, like purging caches or removing event listeners.

66. What is the use of the errorCallback method in LWC?

errorCallback(error, stack) Called when a descendant component throws an error.

67. How to stop executing the method multiple times?

A component is usually rendered many times during the lifespan of an application. To use renderedCallback  hook to perform a one-time operation, use a boolean field like hasRendered to track whether renderedCallback() has been executed. The first time renderedCallback() executes, perform the one-time operation and set hasRendered = true. If hasRendered = true, don’t perform the operation.

68. How to check Component connected to the DOM?

We can use this.isConnected to check whether a component is connected to the DOM or not.

To know more about LWC Lifecycle Hooks



Android Apps,1,Apex,7,Apex Methods,1,Batch Apex,2,Chrome Add-on,1,Chrome browser,1,Coding Best Practices,2,CRM Basics,1,cURL,1,Database Query,1,Dataset,1,Dynamic Apex,3,Dynamic SOQL,1,Einstein Analytics,9,Future Apex,1,Git,1,Google Chrome,1,IDs and Urls Hacks,1,JS for LWC,5,Lightning Components,2,lightning Page,1,Lightning Web Components,14,Linux for Windows users,1,LWC,16,LWC-JEST,7,Queueable Apex,1,Redirect page,1,REGEX,1,REST API,1,Salesforce CRM,1,Salesforce Errors,1,Salesforce Handy Commands,1,Salesforce Interview Questions,14,Salesforce Lightning,1,Salesforce New Features,1,Salesforce Tasks,2,Schedule Apex,1,SLDS,4,SVG Image,3,Test Class,1,Triggers,1,uiObjectInfoApi,1,Visualforce Pages,3,Visualforce Pagination,2,VS Code,2,Wave Analytics,7,Winter Release Notes,1,workbench,1,
SWDC WORLD (Software Development Center Of The World) - is a Multi author and Multi Technology Blog: Salesforce LWC Interview Questions Part - 6
Salesforce LWC Interview Questions Part - 6
LWC Lifecycle Hooks interview questions, constructor,connectedCallback,renderedCallback,render,disconnectedCallback,errorCallback interview questions
SWDC WORLD (Software Development Center Of The World) - is a Multi author and Multi Technology Blog
Loaded All Posts Not found any posts VIEW ALL Readmore Reply Cancel reply Delete By Home PAGES POSTS View All RECOMMENDED FOR YOU LABEL ARCHIVE SEARCH ALL POSTS Not found any post match with your request Back Home Sunday Monday Tuesday Wednesday Thursday Friday Saturday Sun Mon Tue Wed Thu Fri Sat January February March April May June July August September October November December Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec just now 1 minute ago $$1$$ minutes ago 1 hour ago $$1$$ hours ago Yesterday $$1$$ days ago $$1$$ weeks ago more than 5 weeks ago Followers Follow THIS PREMIUM CONTENT IS LOCKED STEP 1: Share to a social network STEP 2: Click the link on your social network Copy All Code Select All Code All codes were copied to your clipboard Can not copy the codes / texts, please press [CTRL]+[C] (or CMD+C with Mac) to copy