If you need a custom pipe, before creating one, consider checking out the NGX Pipes package which has 70+ already implemeted custom pipes.
Here are some examples:
<p>{{ date | timeAgo }}</p>
<!-- Output: "last week" -->
<p>{{ 'foo bar' | ucfirst }}</p>
<!-- Output: "Foo bar" -->
<p>3 {{ 'Painting' | makePluralString: 3 }}</p>
<!-- Output: "3 Paintings" -->
<p>{{ [1, 2, 3, 1, 2, 3] | max }}</p>
<!-- Output: "3" -->翻译自：https://www.30secondsofcode.org/angular/s/reusing-existing-custom-pipes
