Working with TypeScript Decorators

Working with TypeScript Decorators

TypeScript decorators are a powerful feature of the language, allowing developers to extend behavior of functions, classes, and properties. In this blog post, we'll go over what TypeScript decorators are and how they can help you in your development.

What is a Decorator?

A decorator is a special type of function that allows you to “decorate” a class, method, or property. By doing this, you can add extra functionality or modify existing behavior without having to make changes to the original code. They can be used to define custom behavior, like whether a certain function or property is accessible to public users, or even to log when certain functions are called.

How Do I Use Decorators?

In TypeScript, decorators are declared by using the @ symbol with two parentheses. For example, if you wanted to create a decorator to log when a function is called, you could do this:

@logFunction()
function myFunction() {
    console.log("myFunction has been called!");
}

Decorators can also take arguments, which are written between the parentheses. For example, if you wanted to log the name of the function being called, you could do this:

@logFunction(name)
function myFunction() {
    console.log("myFunction has been called!");
}

If you need more flexibility, you can also define your own decorators by creating a function. When you use a custom decorator, the function takes three parameters: target (the class, method, or property being decorated), name (the name of the object being decorated), and descriptor (the descriptor of the object). Here is an example of a custom decorator:

function myDecorator(target: any, name: string, descriptor: PropertyDescriptor) {
    console.log("myDecorator has been called for " + name);
}

Conclusion

TypeScript decorators are a powerful feature of the language and can be very helpful in developing complex applications. If you want to use them, you can either use the built-in decorators or define your own. However you choose to use them, decorators can help provide a cleaner, more maintainable codebase.