typescript decorator

decorator.ts

export function ClassName(name: string) {
	return function actualDecorator<T, U = unknown>(
		constructor: new (...args: T[]) => U,
		arg: ClassDecoratorContext
	) {
		console.log(arg);
		constructor.prototype.className = name;
	};
}

export function traceAsyncMethod(methodName: string) {
	return function actualDecorator<
		This extends { className?: string },
		Args extends unknown[],
		Return
	>(
		originalAsyncMethod: (this: This, ...args: Args) => Promise<Return>,
		arg: ClassMemberDecoratorContext
	) {
		console.log(arg);
		return async function replacementMethod(this: This, ...args: Args): Promise<Return> {
			const className = this.className ?? this.constructor.name;
			const body: Record<string, unknown> = {
				level: 'info',
				className,
				methodName
			};

			console.log({ ...body, message: `Entering ${className}.${methodName}()` });

			const result = await originalAsyncMethod.apply(this, args);

			console.log({ ...body, message: `Exiting ${className}.${methodName}()` });

			return result;
		};
	};
}