Trade

Trade against a Liquidity provider in the TDEX network. This fully implements BOTD#4

The Trade object provides the API using to interact with TDex daemons. The constructor takes a configuration object with the following options:

• providerUrl: the TDex daemon endpoint, hosted by a Liquidity provider.
• explorerUrl: the Esplora endpoint using to get blockchain data.
• utxos: the trader's unspents. You can fetch them with LDK.
• coinSelector: specify the strategy used to select utxos during transaction creation.

const trade = new Trade({
  providerUrl: "provider.tdex.network:9945",
  explorerUrl: "https://blockstream.info/liquid/api",
  utxos: traderUtxos, // an array of UtxoInterface
  coinSelector: greedyCoinSelector(), // this is exported by tdex-sdk
});

utxos are JS objects wrapping utxo's data. They can be fetched without LDK. However, they must be unblinded in case of confidential outputs.

tip

TOR proxy for web clients

Natively, web browsers do not support TOR protocol. That's why we are using a tor-proxy to redirect requests to onion endpoints. By default, clients use https://proxy.tdex.network as proxy. If you want to use your own, you must specify your proxy endpoint in Trade constructor.

Example with a custom proxy hosted at https://my.custom.tor-proxy.endpoint.

const trade = new Trade(tradeOpts, "https://my.custom.tor-proxy.endpoint");

tradeOpts.providerUrl should be an onion endpoint here.

Market

We'll trade on LBTC<->USDT market. MarketInterface describes the market with asset hashes.

const market = {
  baseAsset: "6f0279e9ed041c3d710a9f57d0c02928416460c4b722ae3457a11eec381c526d", // L-BTC
  quoteAsset:
    "c5870288a7c9eb5db398a5b5e7221feb9753134439e8ed9f569b0eea5a423330", // USDT
};

Sell L-BTC

Then, using the Trade instance, we are able to sell 10 000 sats of L-BTC. At this step, you need an IdentityInterface in order to sign the PSET.

// sell ALWAYS send baseAsset and receive quoteAsset
// `trade` will select the baseAsset unspents.
const tradeTxID = await trade.sell({
  market, // our MarketInterface object
  amount: 100000, // expressed in satoshis
  asset: market.baseAsset,
  identity: identityInterface,
});

Buy L-BTC

Contrary to trade.sell, the trade.buy function lets to buy the baseAsset (L-BTC here).

// sell ALWAYS send quoteAsset and receive baseAsset
// `trade` will select the quoteAsset unspents.
const tradeTxID = await trade.buy({
  market, // our MarketInterface object
  amount: 100000, // expressed in satoshis
  asset: market.baseAsset,
  identity: identityInterface,
});

The asset parameter is using to specify the amount of base or quote asset in a trade. Thus, if u want to sell the base asset in order to receive a certain amount of quote asset, you can specify it in sell() parameter object.

// sell baseAsset and receive quoteAsset
const tradeTxID = await trade.sell({
  market,
  amount: 50000,
  asset: market.quoteAsset, // receive 50000 sats of *quoteAsset* but still send *baseAsset*!
  identity: identityInterface,
});

Preview

The trade.preview method can be used to compute market's prices.

const {
  assetToBeSent
  amountToBeSent // amount of baseAsset satoshis to sell in order to receive 50000 quoteAsset
  assetToReceive
  amountToReceive
} = await trade.preview({
  market,
  tradeType: TradeType.SELL,
  amount: 50000,
  asset: market.quoteAsset
});