What are events in LWC?

LWC uses standard DOM events to create and dispatch events. The DOM events system is a programming design pattern that includes these elements. An event name, called a type. A configuration to initialize the event. A JavaScript object that emits the event. For example ? if you change the dispatch statement to this.

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Keeping this in consideration, why would you use aura method?

Use aura:method to define a method as part of a component's API. This enables you to directly call a method in a component's client-side controller instead of firing and handling a component event. What happens when an event is fired? Event is fired means when you generate event via server side objects ( e.g business rule, script includes).

What is Salesforce LDS?

For Lightning components, Salesforce added a new Feature - Lightning Data Service (LDS) in its Winter '17 release. LDS serves as the 'data layer' for Lightning. Without LDS, every Lightning component makes separate calls to the server to fetch the relevant data. How do you communicate with aura and LWC? receiveData(stringToSend) line in the passDataToLWC method in the Aura Components Javascript controller. This is finding the lwc that we imported into our Aura Component by its aura:id and then calling the receiveData method in the LWC (the method with the @api decorator) and passing it data.

Also, how do you create an event in lwc?

To create an event in LWC, use CustomEvent CTOR, and use this. dispatchEvent to fire event. btnHandler function will create and fire a custom event named "uploadevent".