# @bitgo/unspents

The package provides a `Dimensions` class with methods to calculate bitcoin transaction sizes

## Installation

```
npm install --save @bitgo/unspents
```

## Dimensions, Virtual Size Estimation

The transaction vSize is critical to calculating the proper transaction fee.

The class `unspents.Dimensions` provides a class that helps work with the components required
to calculate an accurate estimate of a transaction vSize.

### Examples

```typescript
import { Codes, Dimensions } from '@bitgo/unspents';
// using raw attributes
new Dimensions({
  nP2shInputs: 1,
  nP2shP2wshInputs: 1,
  nP2wshInputs: 1,
  outputs: { count: 1, size: 32 },
});

// calculate from unspents that have `chain` property (see Chain Codes)
Dimensions.fromUnspents(unspent[0]);
Dimensions.fromUnspents(unspents);

// Signed inputs work too
Dimensions.fromInput(inputs[0]);
Dimensions.fromInputs(inputs);

// Transaction outputs
Dimensions.fromOutputs(outputs[0]);
Dimensions.fromOutputs(outputs);
Dimensions.fromOutputOnChain(Codes.p2sh.internal);
Dimensions.fromOutputScriptLength(31);

// Combining dimensions and estimating their vSize
Dimensions.fromUnspents({ unspents })
  .plus(Dimensions.fromOutputOnChain(Codes.p2shP2wsh.internal).times(nOutputs))
  .getVSize();
```

## Continuous Integration

`@bitgo/unspents` uses github actions for continuous integration, which is configured by the `.github/workflows/ci.yml` file in the project root. All changes to the CI process should be done by modifying the `.github/workflows/ci.yml` file.

## `Codes`

The exported `Codes` module is now deprecated.

Please use [`utxo-lib/src/bitgo/wallet/chains`](https://github.com/BitGo/BitGoJS/blob/0439a0d4ffe4a15a9932ed70f98cc5745cc6526f/modules/utxo-lib/src/bitgo/wallet/chains.ts) instead.