Decorators
Decorators provide a way to add annotations and modify classes and class members at design time. They are a special kind of declaration that can be attached to class declarations, methods, accessors, properties, or parameters.
function readonly(target: any, propertyKey: string, descriptor: PropertyDescriptor) {
descriptor.writable = false;
}
class Greeter {
greeting: string;
constructor(message: string) {
this.greeting = message;
}
@readonly
greet() {
return "Hello, " + this.greeting;
}
}
Exercise
Write a decorator called log that logs to the console each time a method is called. Apply this decorator to a method within a class.
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