In the Web of Things (WoT), special communication networks composed of sensor nodes, actuator nodes and service nodes form the basis for new types of web applications, which are directly connected to the real world via sensors and actuators, and can be private, such as smart home apps, personal robotics apps and factory control applications, or public, such as air pollution monitoring systems and city parking management systems.
If you want to become a great app developer, it's not sufficient that you master your favorite programming technologies. It's essential that you understand all basic concepts and techniques, not just in programming, but also in information management.
The concept of a class is fundamental in object-oriented programming. Objects instantiate (or are classified by) a class. A class defines the properties and methods (as a blueprint) for the objects that instantiate it. Having a class concept is essential for being able to implement a data model in the form of model classes within a Model-View-Container (MVC) architecture.
Where is the "model" in AngularJS? The answer to this question is:
AngularJS does not work with a real model but just with a view model. Therefore, it shouldn't be called an MVC framework, and neither an MVW nor an MV* framework, but rather a View-Model-Whatever (or VM*) framework.
In summary, the answer to this question is: because unlike the general concept of an object type or class, the general concept of an association, as defined by UML, does not have a direct computational counterpart, neither in common object-oriented (OO) programming languages, nor in SQL.