Laravel Example

 List the differences between Angular 2 components vs. directives.

1. Observable is a more powerful way of handling HTTP asynchronous requests. Whereas, A promise handles a single event when an asynchronous operation completes or fails.
2. An observable is like a stream which allows passing zero or more events where the callback is called for each event. Whereas, A promise eventually calls the success or failed callback even when you don’t need the notification or the result it provides anymore.
3. Observable works with multiple values for a particular time. Whereas, Promises works with and even returns a single value at a time.
4. Observables can be canceled. Whereas, Promises cannot be canceled.
5. Observable supports map, filter, reduce and similar operators. Whereas, Promises have more readable codes with try/catch and async/await.
6. In observable, one operator ‘retry’ can be used to retry whenever needed. Whereas, Promises cannot be retried. A promise should have access to the original function that returned the promise in order to have a retry capability.

 How to declare a component in Angular 2?

@component ({selector: 'great', template: 'hello {{name}}!'})

Class greet{

Name: string = 'world';

}

 How do you define transition between two states in angular?

function transition (stateChangeExpr: string,steps: AnimationMetadata | 
  AnimationMetadata []):AnimationTransitionMetadata;