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30-seconds-of-code/snippets/dayOfYear.md
Angelos Chalaris 82d59bb8de Add dayOfYear
2018-09-29 13:22:20 +03:00

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### dayOfYear
Gets the day of the year from a `Date` object.
Use `new Date()` and `Date.prototype.getFullYear()` to get the first day of the year as a `Date` object, subtract it from the provided `date` and divide with the milliseconds in each day to get the result.
Use `Math.floor()` to appropriately round the resulting day count to an integer.
```js
const dayOfYear = date => Math.floor(
(date - new Date(date.getFullYear(), 0, 0)) / 1000 / 60 / 60 / 24
);
```
```js
dayOfYear(new Date()); // 272
```