decorators-example.ts

'use strict';

function classDecorator(target: any) {
	console.log('class decorator');
}

function propertyDecorator(target: any, key: string | symbol) {
	console.log('property decorator');
}

function staticMethodDecorator(target: any, key: string | symbol, descriptor: PropertyDescriptor) {
	console.log('static method decorator');
}

function parameterDecorator(target: any, key: string | symbol, index: number) {
	console.log('parameter decorator');
}

function methodDecorator(target: any, key: string, descriptor: PropertyDescriptor) {
	let fn = descriptor.value;

	descriptor.value = function(...args: any[]) {
		console.log('pre method');
		fn.apply(this, args);
		console.log('post method');
	}

	console.log('method decorator');
}

@classDecorator
class Foo {	
	@propertyDecorator
	foo: string;

	@methodDecorator	
	fn(@parameterDecorator arg?: string) {
		this.foo = arg;
		console.log('method call');
	}

	@staticMethodDecorator
	static fn () {
		console.log('static method call');
	}
}


let f = new Foo();
f.fn('bah');
Foo.fn();