According to Angular 2 docs, “Angular pipes, a
way to write display-value transformations that we can declare in our HTML!”
Angular 2 templates use a special Async pipe to
be able to render out Observables.
Syntax:
*ngFor="#obj of
asyncObject | async | custom-Pipe: 'prop1' : 'prop2'"
OR
*ngFor="#obj of (asyncObject
| async)? .prop1? .prop2"
For more detail,