how to use async pipe in typescript code example

Example 1: why async pipe should be used in angular

Async pipe automatically unsubscribes the observable thus saving some lines of code
Async pipe utilizes on push change detection strategy which is good for performance.

Example 2: javascript pipe async functions

const pipeAwait = (...fns) => param => fns.reduce(async (result, next) => next(await result), param)