Difference between subject and behaviour subject

Difference between subject and behaviour subject

Source: Difference between subject and behaviour subject

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In RxJS, a popular library for reactive programming in JavaScript, there are two types of subjects: Subject and BehaviorSubject. Both are implementations of the `Subject` class but have some key differences in behavior.

1. Subject: A `Subject` is a multicast observable that can be subscribed to by multiple observers. It acts as both an observable and an observer, meaning you can subscribe to it to receive values and also push values to it using its `next()` method. When a `Subject` emits a new value, all of its subscribed observers will receive that value.
2. 2. BehaviorSubject: A `BehaviorSubject` is a type of `Subject` that has a notion of “current value”. It maintains and emits the latest value to any new subscribers. When a `BehaviorSubject` is created, it requires an initial value. Any subscriber that subscribes to a `BehaviorSubject` will immediately receive the current value or the latest emitted value.

Here are the key differences between `Subject` and `BehaviorSubject`:

— Initial Value: `Subject` doesn’t have an initial value, while `BehaviorSubject` requires an initial value during its creation.