PercentPipe

{{value_expression | percent [:'digitsInfo' [:local]}}

src/app/app.component.html

@@ -1,2 +1 @@
-<div>預設數值顯示：{{ pi | number }}</div>
-<div>指定整數與小數長度：{{ pi | number: '4.1-5' }}</div>
+<div>百分率：{{ pi | percent: '2.2-4' }}</div>