Observer

An Observer ¹ is an entity that receives values from an Observable. It consists of a set of callback functions, each handling a different type of notification the Observable can send:

• next(value): Processes the emitted value.
• error(err): Handles any error that occurs during execution.
• complete(): Executes when the Observable has finished sending data.

Here’s an example of how an Observer is structured:

const observer = {
  next: value => console.log('Received value:', value),
  error: err => console.error('Error encountered:', err),
  complete: () => console.log('Observable has completed'),
};

This observer can then be used to subscribe to an Observable, listening for values, errors, or completion signals.

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🔗 Sources

Footnotes

1. RxJS - Observer ↩