.observe({ action: (response) => { this.updateData = response.Items; }. what comes after this

I need some guidance on what comes next within the callback function

.subscribe({
       next: (data) => {
         this.newData = data.Items;
       }

Answer №1

Each time the observable linked to this subscribe method emits a new value, a callback function is executed.

This concept is demonstrated clearly in the following code snippet:

let observer;
let observable = new Observable(o => observer = o);
observable.subscribe({
  next: itm => console.log("New item", itm); //Triggered by Callback #1
  error: e => console.error("Something went wrong: ", e), //Triggered by Callback #2
  complete: lastValue => console.log(`Observable terminated with last value`:, lastValue); //Triggered by Callback #3
});

observer.next(1); //Triggers Callback #1,
observer.next("foo"); //Triggers Callback #2
observer.error("Problem"); //Triggers Callback #2
observer.complete(); // Terminates the observable, preventing further calls to next

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