RelativeRange
=============

Calculate a date range relative to a certain moment.

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**Contents**

- [Installation](#installation)
  - [npm](#npm)
  - [yarn](#yarn)
- [Initiation](#initiation)
- [Basic usage](#basic-usage)
  - [Previous](#previous)
  - [Next](#next)
  - [Current](#current)
  - [Combinations](#combinations)
- [Custom](#custom)
  - [Options](#options)
- [Formatting](#formatting)
  - [#format](#format)
  - [#locale](#locale)
  - [#toArray](#toarray)
- [Integrations](#integrations)
  - [moment.range](#momentrange)

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## Installation

### npm
```bash
npm i -S moment-relative-range
```

### yarn
```bash
yarn add moment-relative-range
```

## Initiation
```js
import moment from 'moment';
import { extendMoment } from 'moment-relative-range';

extendMoment(moment);
```

## Basic usage

### Previous
```js
var range = moment().previous(5, 'days');

// range.start = 6 days ago
// range.end = yesterday
// range.length = 5

var previousMonth = range.previous(1, 'months');

// The new range will be relative to the old one
// previousMonth.start = start of 1 months ago
// previousMonth.end = end of last month
// previousMonth.length = the length of the last month in days

var previousYear = previousMonth.previous(1, 'year');

// previousYear.start = start of the year before the previous month
// etc.
```

### Next

```js
var range = moment().next(2, 'month');

// range.start = 1st day of next month
// range.end = last day of the month after the next
```

### Current
You can use `moment().current(measure)`:

```js
var thisMonth = moment().current('month');

// thisMonth.start = start of the month
// thisMonth.end = today
// thisMonth.length = the number of days since the start of this month
```

### Combinations

```js
moment()
    .previous(1, 'year') // Last year
    .current('month') // Last years December
    .previous(1, 'month') // Last years November
    .next(1, 'week'); // First week of December last year
```

## Custom
It's also possible to construct a range yourself:

```js
import RelativeRange from 'moment-relative-range';

var range = new RelativeRange({
    date: new Date(),
    units: 5,
    measure: 'days'
});

// The results are the same as above
```

### Options

- `date` (Date): The date to calculate the range from. _required_
- `measure` (String): Things like month, year, day, isoWeek. _required_
- `units` (Number): The amount of measures. _required_
- `margin` (Number): A gap between the the date and the end date of the range, in number of days. _optional_
- `fixedStart` (Date): A fixed start date. _optional_

## Formatting

### #format

```js
moment().current('month').format('ll'); // 'Jan 1 - 31, 2000'
```

Default format is `ll`. There are two custom formats supported: `r` and `R`.

- `r`: today, yesterday, last month, coming week, etc.
- `R`: this day, previous 1 day, previous month, next week, etc.

### #locale
You can set the locale of a range by using the `#locale` function. This works the same as for a normal moment.

```js
moment().current('month').locale('en').format(); // 'Jan 1 - 31, 2000'
moment().current('month').locale('nl').format(); // '1 - 31 jan., 2000'
```

### #toArray

```js
moment().current('month').toArray(); // ['YYYY-MM-DD', 'YYYY-MM-DD']
```

`toArray` takes an optional `format` parameter. Defaults to `YYYY-MM-DD`;

## Integrations

### moment.range

There is a great package called [moment-range](https://www.npmjs.com/package/moment-range), which works great with this package:

```js
import { extendMoment as extendWithRange } from 'moment-range';

extendWithRange(moment);

const last5DaysRange = moment().previous(5, 'days');

const momentRange = moment.range(last5DaysRange.toArray());

const last5Days = momentRange.by('day'); // [day1, day2, day3, day4, day5]

const relativeRange = new RelativeRange(momentRange);

relativeRange.current('month'); // etc.
```