Reactive programming
The best way to understand any new paradigm or concept is to reason about its existence. For this let's think of a very common and simple scenario, as shown here:
You might have come across the form behavior shown in the preceding figure. There's an agreement to read and then we click on the checkbox to agree to it so that we can proceed further. On the left-hand side, the checkbox is unchecked. Hence, based on its value, we have set the visibility of the Continue button (currently for the unchecked box) to false. Once we click and set the checkbox value to true, the visibility of the Continue button also becomes true. What is happening is when we click on checkbox, it emits an event with its value, that is, true/false. Now, based on its value, we can set the button's visibility to true/false. This is an example of observing events of a simple checkbox and making use of the event's value. If you picture this, it might look as follows:
The following diagram shows the Checkbox...
