What are parameter decorators in TypeScript?

Can you explain what parameter decorators are in TypeScript?

Parameter decorators are special functions that can be applied to the parameters of a class method. They allow you to modify or observe the parameters passed to the method.

Can you give me an example of how to use a parameter decorator?

Sure! Here's a simple example:

function Log(target: any, propertyKey: string, parameterIndex: number) {
    console.log(`Parameter at index ${parameterIndex} in method ${propertyKey} was decorated.`);
}

class Example {
    method(@Log param: string) {
        console.log(param);
    }
}

In this example, the Log decorator logs the index of the parameter whenever the method is called.

What are some use cases for parameter decorators?

Parameter decorators can be used for logging, validation, or injecting dependencies in frameworks like Angular. They help in enhancing the functionality of methods without modifying their core logic.