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+---
+title: formatSeconds
+tags: date,math,string,intermediate
+---
+
+Returns the ISO format of the given number of seconds.
+
+- Divide `s` with the appropriate values to obtain the appropriate values for `hour`, `minute` and `second`.
+- Store the `sign` in a variable to prepend it to the result.
+- Use `Array.prototype.map()` in combination with `Array.prototype.floor()` and `String.prototype.padStart()` to stringify and format each segment.
+- Use `String.prototype.join(':')` to combine the values into a string.
+
+```js
+const formatSeconds = s => {
+  const [hour, minute, second, sign] =
+    s > 0
+      ? [s / 3600, (s / 60) % 60, s % 60, '']
+      : [-s / 3600, (-s / 60) % 60, -s % 60, '-'];
+
+  return (
+    sign +
+    [hour, minute, second]
+      .map(v => `${Math.floor(v)}`.padStart(2, '0'))
+      .join(':')
+  );
+};
+```
+
+```js
+formatSeconds(200); // '00:03:20'
+formatSeconds(-200); // '-00:03:20'
+formatSeconds(99999); // '27:46:39'
+```