Angular Interview Practice

How does Angular identify the type of directive being used?

1. By analyzing the component logic

2. Through naming conventions

3. By the presence of specific decorators

4. By analyzing HTML attributes

The correct answer is: By the presence of specific decorators

Angular identifies the type of directive being used primarily through the presence of specific decorators. Decorators such as @Component, @Directive, and @Pipe are fundamental in defining how Angular processes and treats different classes within the application. When you create a component, for instance, the @Component decorator specifies that a class is a component, along with its associated metadata such as selectors, template URLs, and styles. Similarly, for directives, the @Directive decorator tells Angular that this particular class is a directive, which may modify the behavior of elements in the DOM or change their appearance. This mechanism of using decorators is essential because it allows Angular to leverage TypeScript's metadata reflection capabilities. It knows how to treat a class based on the decorators applied to it, allowing for a clear differentiation between components, directives, and other constructs such as pipes. The clarity in how directives and components are defined ensures that Angular can manage the application effectively, adhering to the conventions of component-based architecture. In contrast, options such as analyzing component logic, employing naming conventions, or examining HTML attributes don't directly dictate the type of directive being used in a usual Angular setup. While naming conventions and HTML attributes might have some relevance in specific contexts—like when using selectors for components—they do