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snippets/js/s/format-duration.md

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+---
+title: Format duration
+type: snippet
+language: javascript
+tags: [date,math,string]
+cover: clock
+dateModified: 2020-10-22T20:23:47+03:00
+---
+
+Returns the human-readable format of the given number of milliseconds.
+
+- Divide `ms` with the appropriate values to obtain the appropriate values for `day`, `hour`, `minute`, `second` and `millisecond`.
+- Use `Object.entries()` with `Array.prototype.filter()` to keep only non-zero values.
+- Use `Array.prototype.map()` to create the string for each value, pluralizing appropriately.
+- Use `Array.prototype.join()` to combine the values into a string.
+
+```js
+const formatDuration = ms => {
+  if (ms < 0) ms = -ms;
+  const time = {
+    day: Math.floor(ms / 86400000),
+    hour: Math.floor(ms / 3600000) % 24,
+    minute: Math.floor(ms / 60000) % 60,
+    second: Math.floor(ms / 1000) % 60,
+    millisecond: Math.floor(ms) % 1000
+  };
+  return Object.entries(time)
+    .filter(val => val[1] !== 0)
+    .map(([key, val]) => `${val} ${key}${val !== 1 ? 's' : ''}`)
+    .join(', ');
+};
+```
+
+```js
+formatDuration(1001); // '1 second, 1 millisecond'
+formatDuration(34325055574);
+// '397 days, 6 hours, 44 minutes, 15 seconds, 574 milliseconds'
+```