Pub/Sub, which means Publish-Subscribe, uses a more structured approach. Instead of depending on DOM components, it uses a central message bus, similar to an events message board. Here is the summary:

- Publishers: These are the event announcers who broadcast messages (events) via the messaging bus.
- Subscribers: These are the visitors who registered to receive specific announcements (events). When a relevant interaction comes, subscribers get notified and can take action.

Problem: Implement a simple version of Promise:

The Promise object is an asynchronous programming solution for handling asynchronous events. Promise objects can represent the status of an asynchronous operation, including:

- pending
- fulfilled
- rejected

Analysis:

🌶The MyPromise class is a custom Promise class whose constructor accepts an executor function as a parameter.
🌽The executor function in the constructor will be executed immediately and accepts two parameters, resolve and reject, which are used to modify the state of the Promise.
🍞The resolve method is used to modify the Promise’s status from “pending” to “fulfilled” and pass the value to subsequent handlers.
🥚The reject method is used to modify the Promise’s status from “pending” to “rejected” and pass the reason to the subsequent handler.
🍳The then method is used to register a callback function to be executed when the Promise is completed or rejected. It accepts two parameters: onFulfilled and onRejected, which are called when the Promise is completed or rejected respectively.
🥩The then method returns a new MyPromise instance to support chained calls. If onFulfilled or onRejected returns a value, it will be used as the resolved value for the next MyPromise instance.
🍔The catch method is the shorthand form of then(null, onRejected).
🍕The isFulfilled method is used to check whether the Promise is in the fulfilled state.
🌮The isRejected method is used to check whether the Promise is in the rejected state.

Computed Signals: Derived Signal

Function: Computed signals represent values derived from other signals. Think of them as formulas that take existing signals as inputs and produce a new output value.
Creation: You define them using the computed function, specifying a derivation function that outlines how the computed value is calculated.
Benefits:
Lazy Evaluation: Computed signals are calculated only when their value is needed. This avoids unnecessary computations.
Memoization: Subsequent reads of the computed signal with the same dependencies return the cached value, improving performance.
Dependency Tracking: Angular automatically tracks which signals a computed signal depends on. When any of those signals change, the computed signal is automatically recalculated.

Effects: Actions Triggered by Signal Changes

Function: Effects are functions that execute in response to changes in signals. They typically perform side effects like logging, interacting with external APIs, or updating local storage.
Creation: You create effects using the effect function. This function can optionally accept a onCleanup function for managing long-running operations.
Benefits:
Reactivity: Effects automatically run whenever their dependent signals change, ensuring your application stays up-to-date.
Asynchronous Execution: Effects run asynchronously during change detection, preventing them from blocking the main thread.

On the first screen, we have a ParentComponent that passes data to a ChildComponent, which in turn passes the data to an InnerChildComponent. This is a simple example.

On the second screen, the example will help you to remove prop drilling from your Angular applications and make your code more maintainable and easier to understand.

Testing lies at the heart of building robust and reliable Angular applications.