Format duration object (#13538)

src/common/datetime/format_duration.ts

@@ -0,0 +1,28 @@
+import { HaDurationData } from "../../components/ha-duration-input";
+
+const leftPad = (num: number) => (num < 10 ? `0${num}` : num);
+
+export const formatDuration = (duration: HaDurationData) => {
+  const d = duration.days || 0;
+  const h = duration.hours || 0;
+  const m = duration.minutes || 0;
+  const s = duration.seconds || 0;
+  const ms = duration.milliseconds || 0;
+
+  if (d > 0) {
+    return `${d} days ${h}:${leftPad(m)}:${leftPad(s)}`;
+  }
+  if (h > 0) {
+    return `${h}:${leftPad(m)}:${leftPad(s)}`;
+  }
+  if (m > 0) {
+    return `${m}:${leftPad(s)}`;
+  }
+  if (s > 0) {
+    return `${s} seconds`;
+  }
+  if (ms > 0) {
+    return `${ms} milliseconds`;
+  }
+  return null;
+};