Update formatSeconds.md

snippets/formatSeconds.md

@@ -1,26 +1,33 @@
 ---
 title: formatSeconds
-tags: date,math,string
+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 "HH:mm:ss".
-- Use `Array.prototype.map()` to create the string for each value, and pads it to `2` digits.
-- Use `String.prototype.join(', ')` to combine the values into a string.
+- 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 => {
-  if (s < 0) s = 0;
-  
-  return [s / 3600, s / 60 % 60, s % 60]
-    .map(v => `${Math.floor(v).toString().padStart(2, '0')}`)
-    .join(':');
+  const [hour, minute, second, sign] =
+    s > 0
+      ? [s / 3600, (s / 60) % 60, s % 60, '']
+      : [-s / 3600, (-s / 60) % 60, -s % 60, '-'];
+
+  return (
+    sign +
+    [hour, minute, second]
+      .map(v => `${Math.floor(v)}`.padStart(2, '0'))
+      .join(':')
+  );
 };
 ```
 
 ```js
-formatSeconds(-200); // "00:00:00"
-formatSeconds(200); // "00:03:20"
-formatSeconds(99999); // "27:46:39"
+formatSeconds(200); // '00:03:20'
+formatSeconds(-200); // '-00:03:20'
+formatSeconds(99999); // '27:46:39'
 ```