Improve time conversion logic and add full tests

Author: ChinweP

Sprint-2/5-stretch-extend/format-time.js

@@ -23,3 +23,64 @@ console.assert(
   currentOutput2 === targetOutput2,
   `current output: ${currentOutput2}, target output: ${targetOutput2}`
 );
+
+// Midnight
+console.assert(
+  formatAs12HourClock("00:00") === "12:00 am",
+  "00:00 should be 12:00 am"
+);
+
+// Noon
+console.assert(
+  formatAs12HourClock("12:00") === "12:00 pm",
+  "12:00 should be 12:00 pm"
+);
+
+// Minutes included
+console.assert(
+  formatAs12HourClock("14:45") === "2:45 pm",
+  "14:45 should be 2:45 pm"
+);
+
+// Single-digit hour AM
+console.assert(
+  formatAs12HourClock("09:30") === "9:30 am",
+  "09:30 should be 9:30 am"
+);
+
+// Single-digit hour PM
+console.assert(
+  formatAs12HourClock("13:05") === "1:05 pm",
+  "13:05 should be 1:05 pm"
+);
+
+// Edge: 12:59 PM
+console.assert(
+  formatAs12HourClock("12:59") === "12:59 pm",
+  "12:59 should be 12:59 pm"
+);
+
+// Edge: 00:59 AM
+console.assert(
+  formatAs12HourClock("00:59") === "12:59 am",
+  "00:59 should be 12:59 am"
+);
+
+function formatAs12HourClock(time) {
+  const [hourStr, minuteStr] = time.split(":");
+  let hours = Number(hourStr);
+  const minutes = minuteStr;
+
+  let period = "am";
+
+  if (hours === 0) {
+    hours = 12; // midnight
+  } else if (hours === 12) {
+    period = "pm"; // noon
+  } else if (hours > 12) {
+    hours -= 12;
+    period = "pm";
+  }
+
+  return `${hours}:${minutes} ${period}`;
+}