denoland-deno/std/datetime/README.md

# datetime

Simple helper to help parse date strings into `Date`, with additional functions.

## Usage

The following symbols from
[unicode LDML](http://www.unicode.org/reports/tr35/tr35-dates.html#Date_Field_Symbol_Table)
are supported:

- `yyyy` - numeric year.
- `yy` - 2-digit year.
- `M` - numeric month.
- `MM` - 2-digit month.
- `d` - numeric day.
- `dd` - 2-digit day.

- `H` - numeric hour (0-23 hours).
- `HH` - 2-digit hour (00-23 hours).
- `h` - numeric hour (1-12 hours).
- `hh` - 2-digit hour (01-12 hours).
- `m` - numeric minute.
- `mm` - 2-digit minute.
- `s` - numeric second.
- `ss` - 2-digit second.
- `S` - 1-digit fractionalSecond.
- `SS` - 2-digit fractionalSecond.
- `SSS` - 3-digit fractionalSecond.

- `a` - dayPeriod, either `AM` or `PM`.

- `'foo'` - quoted literal.
- `./-` - unquoted literal.

### parse

Takes an input `string` and a `formatString` to parse to a `date`.

```ts
import { parse } from 'https://deno.land/std/datetime/mod.ts'

parse("20-01-2019", "dd-MM-yyyy") // output : new Date(2019, 0, 20)
parse("2019-01-20", "yyyy-MM-dd") // output : new Date(2019, 0, 20)
parse("2019-01-20", "dd.MM.yyyy") // output : new Date(2019, 0, 20)
parse("01-20-2019 16:34", "MM-dd-yyyy HH:mm") // output : new Date(2019, 0, 20, 16, 34)
parse("01-20-2019 04:34 PM", "MM-dd-yyyy hh:mm a") // output : new Date(2019, 0, 20, 16, 34)
parse("16:34 01-20-2019", "HH:mm MM-dd-yyyy") // output : new Date(2019, 0, 20, 16, 34)
parse("01-20-2019 16:34:23.123", "MM-dd-yyyy HH:mm:ss.SSS") // output : new Date(2019, 0, 20, 16, 34, 23, 123)
...
```

### format

Takes an input `date` and a `formatString` to format to a `string`.

```ts
import { format } from "https://deno.land/std/datetime/mod.ts";

format(new Date(2019, 0, 20), "dd-MM-yyyy"); // output : "20-01-2019"
format(new Date(2019, 0, 20), "yyyy-MM-dd"); // output : "2019-01-20"
format(new Date(2019, 0, 20), "dd.MM.yyyy"); // output : "2019-01-20"
format(new Date(2019, 0, 20, 16, 34), "MM-dd-yyyy HH:mm"); // output : "01-20-2019 16:34"
format(new Date(2019, 0, 20, 16, 34), "MM-dd-yyyy hh:mm a"); // output : "01-20-2019 04:34 PM"
format(new Date(2019, 0, 20, 16, 34), "HH:mm MM-dd-yyyy"); // output : "16:34 01-20-2019"
format(new Date(2019, 0, 20, 16, 34, 23, 123), "MM-dd-yyyy HH:mm:ss.SSS"); // output : "01-20-2019 16:34:23.123"
format(new Date(2019, 0, 20), "'today:' yyyy-MM-dd"); // output : "today: 2019-01-20"
```

### dayOfYear

Returns the number of the day in the year.

```ts
import { dayOfYear } from "https://deno.land/std/datetime/mod.ts";

dayOfYear(new Date("2019-03-11T03:24:00")); // output: 70
```

### weekOfYear

Returns the ISO week number of the provided date (1-53).

```ts
import { weekOfYear } from "https://deno.land/std/datetime/mod.ts";

weekOfYear(new Date("2020-12-28T03:24:00")); // Returns 53
```