# Unit
Unit is a utility for handling and converting Gewel units. We strongly recommend to always use adams to represent amount inside your application and only convert them to other units in the front-end.

To understand the need of using the `Unit` class when dealing with unit conversions, see this example:

```
> 81.99 * 100000 // wrong
8198999.999999999
> var Unit = gewelcore.Unit;
> Unit.fromMilis(81.99).toAdams() // correct
8199000
```

## Supported units
The supported units are GWL, mGWL, uGWL and adams. The codes for each unit can be found as members of the Unit class.

```javascript
var gwlCode = Unit.GWL;
var mgwlCode = Unit.mGWL;
var ugwlCode = Unit.uGWL;
var adamsCode = Unit.adams;
```

## Creating units
There are two ways for creating a unit instance. You can instantiate the class using a value and a unit code; alternatively if the unit it's fixed you could you some of the static methods. Check some examples below:

```javascript
var unit;
var amount = 100;

// using a unit code
var unitPreference = Unit.GWL;
unit = new Unit(amount, unitPreference);

// using a known unit
unit = Unit.fromGWL(amount);
unit = Unit.fromMilis(amount);
unit = Unit.fromMicros(amount);
unit = Unit.fromAdams(amount);
```

## Conversion
Once you have a unit instance, you can check its representation in all the available units. For your convenience the classes expose three ways to accomplish this. Using the `.to(unitCode)` method, using a fixed unit like `.toAdams()` or by using the accessors.

```javascript
var unit;

// using a unit code
var unitPreference = Unit.GWL;
value = Unit.fromAdams(amount).to(unitPreference);

// using a known unit
value = Unit.fromGWL(amount).toGWL();
value = Unit.fromGWL(amount).toMilis();
value = Unit.fromGWL(amount).toMicros();
value = Unit.fromGWL(amount).toAdams();

// using accessors
value = Unit.fromGWL(amount).GWL;
value = Unit.fromGWL(amount).mGWL;
value = Unit.fromGWL(amount).micros;
value = Unit.fromGWL(amount).adams;
```

## Using a fiat currency
The unit class also provides a convenient alternative to create an instance from a fiat amount and the corresponding GWL/fiat exchange rate. Any unit instance can be converted to a fiat amount by providing the current exchange rate. Check the example below:

```javascript
var unit, fiat;
var amount = 100;
var exchangeRate = 350;

unit = new Unit(amount, exchangeRate);
unit = Unit.fromFiat(amount, exchangeRate);

fiat = Unit.fromMicros(amount).atRate(exchangeRate);
fiat = Unit.fromMicros(amount).to(exchangeRate);
```