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TS Decorators

TypeScript Decorators

TypeScript decorators add metadata used in Angular and experimental APIs.

What are TypeScript Decorators?

TypeScript decorators are a special kind of declaration that can be attached to a class, method, accessor, property, or parameter. They provide a way to add metadata or modify the behavior of the item they are attached to. Decorators are widely used in frameworks like Angular to enhance functionality.

Syntax of a Decorator

Decorators are special functions prefixed with the @ symbol, followed by the decorator name. They can be applied to classes, methods, properties, and parameters. Here is the basic syntax:

Types of Decorators

There are several types of decorators in TypeScript:

  • Class Decorators: Used to observe, modify, or replace a class definition.
  • Method Decorators: Used to modify the method definition or its metadata.
  • Accessor Decorators: Used to modify the getter/setter method of a property.
  • Property Decorators: Used to observe or modify a property.
  • Parameter Decorators: Used to observe or modify the parameter of a method.

Creating a Class Decorator

Let's create a simple class decorator. Class decorators are applied to the constructor of the class and can be used to log information about the class.

Using Decorators in Angular

In Angular, decorators are used to attach metadata to classes to configure them as components, directives, pipes, etc. The @Component decorator is one of the most commonly used decorators in Angular.

Conclusion

TypeScript decorators provide a powerful way to add metadata and modify the behavior of classes and members. They are essential in frameworks like Angular and are also useful in many other scenarios. As decorators are still an experimental feature, it is important to understand how they work and their potential uses.

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