What are custom decorators in Angular and how do I use them?

What are custom decorators in Angular and how do I use them?

Custom decorators in Angular are functions that can modify the behavior of classes, methods, or properties. They allow you to add metadata or modify the functionality of components, directives, or services.

Can you give me an example of a custom decorator?

Sure! Here's a simple example of a custom decorator that logs the method calls of a class:

function LogMethodCalls(target: any, propertyKey: string, descriptor: PropertyDescriptor) {
    const originalMethod = descriptor.value;
    descriptor.value = function(...args: any[]) {
        console.log(`Calling ${propertyKey} with arguments:`, args);
        return originalMethod.apply(this, args);
    };
}

How do I apply this decorator to a method?

You can apply the decorator by simply placing it above the method you want to decorate, like this:

class MyClass {
    @LogMethodCalls
    myMethod(arg1: string, arg2: number) {
        // method implementation
    }
}

Are there any built-in decorators in Angular?

Yes, Angular provides several built-in decorators like @Component, @Injectable, and @Directive, which are used to define components, services, and directives respectively.