index.ts

import Lifi, {
  ChainId,
  CoinKey,
  ConfigUpdate,
  Execution,
  ExecutionSettings,
  findDefaultToken,
  Route
} from "@lifi/sdk";
import { providers, Signer, Wallet } from 'ethers';

const mnemonic = process.env.MNEMONIC || "";

async function demo() {
  // setup wallet
  if (!process.env.MNEMONIC) {
    console.warn(
      'Please specify a MNEMONIC phrase in your environment variables: `export MNEMONIC="..."`'
    );
    return;
  }
  console.log(">> Setup Wallet");
  const provider = new providers.JsonRpcProvider(
    "https://polygon-rpc.com/",
    137
  );
  const wallet = Wallet.fromMnemonic(mnemonic).connect(provider);

  // get Route
  console.log(">> Request route");
  const routeRequest = {
    fromChainId: ChainId.POL, // Polygon
    fromAmount: "1000000", // 1 USDT
    fromTokenAddress: findDefaultToken(CoinKey.USDT, ChainId.POL).address,
    toChainId: ChainId.DAI, // xDai
    toTokenAddress: findDefaultToken(CoinKey.USDT, ChainId.DAI).address,
    options: {
      slippage: 0.03, // = 3%
      allowSwitchChain: false, // execute all transaction on starting chain
      exchanges: {
        allow: [], // only find direct transfers
      },
    },
  };
  
  // STEP 1: Initialize the API

  // ☝️ This configuration is totally optional! ------------------------------------
  const optionalConfigs: ConfigUpdate = {
    apiUrl: 'https://li.quest', // DEFAULT production endpoint
    rpcs: { // You can provide custom RPCs
      137: ['https://polygon-rpc.com/'] 
    },
    multicallAddresses: { // You can provide custom addresses for multicall
      137: '0x02817C1e3543c2d908a590F5dB6bc97f933dB4BD'
    },
    defaultExecutionSettings: { // You can provide default execution settings @see {ExecutionSettings}
      updateCallback: (route: Route):void => {
        console.log('>> Route updated', route);
      },
      switchChainHook: (requiredChainId: number):Promise<Signer | undefined> => {
        console.log('>> Switching to chain', requiredChainId);
        return Promise.resolve(wallet);
      },
      infiniteApproval: false, // DEFAULT false
    } 
  }
  // ---------------------------------------------------------------------------

  const api = new Lifi(optionalConfigs);

  // STEP 2: Request a route
  const routeResponse = await api.getRoutes(routeRequest);
  const route = routeResponse.routes[0];
  console.log(">> Got Route");
  console.log(route);

  // STEP 3: Execute the route
  console.log(">> Start Execution");

  // These are optonal settings for execution ------------------------------------
  const settings: ExecutionSettings = {
    updateCallback: (updatedRoute) => {
      let lastExecution: Execution | undefined = undefined;
      for (const step of updatedRoute.steps) {
        if (step.execution) {
          lastExecution = step.execution;
        }
      }
      console.log(lastExecution);
    },
    switchChainHook: async (requiredChainId: number) => {
      console.log(">>Switching Chains");
      const provider = new providers.JsonRpcProvider(
        "https://rpc.xdaichain.com/",
        requiredChainId
      );
      const wallet = Wallet.fromMnemonic(mnemonic).connect(provider);
      return wallet;
    },
  };
  // ---------------------------------------------------------------------------

  await api.executeRoute(wallet, route, settings);

  console.log(">> Done");
}

demo();