Loading-indicator Decorators in Angular 2/4

loading-indicator.ts

export function LoadingIndicator(): MethodDecorator {
    return function (target: Object, propertyKey: string | symbol, descriptor) {
        const originalMethod = descriptor.value;

        descriptor.value = function (...args) {
            // Inject your show loading function HERE
            const subs = originalMethod.apply(this, args);

            // If it's using do operator
            if (subs.subscribe) {
                subs.subscribe(() => {
                    // Stop your show loading function HERE
                });
            } else {
                // If it's using subscribe
                const _interval = setInterval(() => {
                    if (subs.isStopped) {
                        // Or stop your show loading function HERE
                        clearInterval(_interval);
                    }
                }, 50);
            };
        }
    };
};