> ## Documentation Index
> Fetch the complete documentation index at: https://docs.saucerswap.finance/llms.txt
> Use this file to discover all available pages before exploring further.

# Swap HBAR for tokens (V2)

> Swap HBAR for HTS tokens through the SaucerSwap V2 SwapRouter using exactInput and exactOutput multicalls with refundETH, with TypeScript code examples.

Below are two methods available to swap HBAR for tokens:

* [Swap exact HBAR for tokens](/developers/v2/swap/swap-hbar-for-tokens#swap-exact-hbar-for-tokens)
* [Swap HBAR for exact tokens](/developers/v2/swap/swap-hbar-for-tokens#swap-hbar-for-exact-tokens)

<Info>
  Contract ID: [SaucerSwapV2SwapRouter](https://hashscan.io/mainnet/contract/0.0.3949434)
</Info>

<Note>
  Consider the token's decimal places when determining the output amount.
</Note>

<Note>
  The output values should be in the token's smallest unit. For the SAUCE token, which has 6 decimal places, an input of 123.45 SAUCE should be entered as 123450000 (123.45 multiplied by 10^6).
</Note>

<Warning>
  Ensure that the "**to**" account has the output token id associated prior to executing the swap. Failure to do so will result in a `TOKEN_NOT_ASSOCIATED_TO_ACCOUNT` error.
</Warning>

<Tip>
  When providing HBAR in the path array, use the Wrapped HBAR token id ([WHBAR](https://hashscan.io/mainnet/token/0.0.1456986)).
</Tip>

## Swap exact HBAR for tokens

Swap an exact amount of HBAR for a minimum token amount

Solidity function name: `exactInput`

| Struct Parameter Name | Description                                                 |
| --------------------- | ----------------------------------------------------------- |
| *bytes path*          | A bytes array representing a route path including fees data |
| *recipient*           | EVM address of the token recipient                          |
| *deadline*            | Deadline in Unix seconds                                    |
| *amountIn*            | The exact input token amount in its smallest unit           |
| *amountOutMinimum*    | The minimum token amount to receive in its smallest unit    |

<CodeGroup>
  ```solidity ISwapRouter.sol theme={null}
  struct ExactInputParams {
    bytes path;
    address recipient;
    uint256 deadline;
    uint256 amountIn;
    uint256 amountOutMinimum;
  }

  function exactInput(ExactInputParams calldata params) external payable returns (uint256 amountOut);
  ```

  ```solidity SwapRouter.sol theme={null}
  /// @inheritdoc ISwapRouter
  function exactInput(ExactInputParams memory params)
    external
    payable
    override
    checkDeadline(params.deadline)
    returns (uint256 amountOut)
  {
    address payer = msg.sender; // msg.sender pays for the first hop

    while (true) {
      bool hasMultiplePools = params.path.hasMultiplePools();

      // the outputs of prior swaps become the inputs to subsequent ones
      params.amountIn = exactInputInternal(
        params.amountIn,
        hasMultiplePools ? address(this) : params.recipient, // for intermediate swaps, this contract custodies
        0,
        SwapCallbackData({
          path: params.path.getFirstPool(), // only the first pool in the path is necessary
          payer: payer
        })
      );

      // decide whether to continue or terminate
      if (hasMultiplePools) {
        payer = address(this); // at this point, the caller has paid
        params.path = params.path.skipToken();
      } else {
        amountOut = params.amountIn;
        break;
      }
    }

    require(amountOut >= params.amountOutMinimum, 'Too little received');
  }
  ```
</CodeGroup>

<Warning>
  Set the minimum output token amount (`amountOutMinimum`) with caution.

  A high minimum might lead to a swap failure due to insufficient liquidity or rapid price movements. Conversely, setting the minimum too low can expose you to significant slippage, potentially resulting in a financial loss as you might receive far fewer tokens than expected.
</Warning>

<Tip>
  It is recommended to include `refundETH` in the multicall in case excess HBAR was sent to the contract.
</Tip>

<Tip>
  The data passed to the 'path' parameter follows this format: \[token, fee, token, fee, token, ...], with each 'token' in the route being 20 bytes long and each 'fee' being 3 bytes long. Example, 0x0001F4 (500) for a 0.05% fee.
</Tip>

### Code overview

<Tabs>
  <Tab title="JavaScript SDK">
    Resources:

    * [SaucerSwap deployed contract IDs](/developers/contracts)
    * [Hedera JavaScript SDK](https://github.com/hashgraph/hedera-sdk-js)
    * [Ethers.js docs (v6)](https://docs.ethers.org/v6/)
    * [Associate tokens to an account](https://docs.hedera.com/hedera/sdks-and-apis/sdks/token-service/associate-tokens-to-an-account)

    *Note: The Hedera JavaScript SDK currently does not support passing complex contract function parameters. Instead, use Ethers.js or Web3.js to obtain the encoded function data and pass that data as a function parameter.*

    ```typescript theme={null}
    import * as ethers from 'ethers'; //V6
    import {
      ContractExecuteTransaction,
      TokenAssociateTransaction
    } from '@hashgraph/sdk';

    //Client pre-checks:
    // - Output token is associated

    //load ABI data containing SwapRouter, PeripheryPayments and Multicall functions
    const abiInterfaces = new ethers.Interface(abi);

    //ExactInputParams
    const params = {
      path: routeDataWithFee, //'0x...'
      recipient: recipientAddress, //'0x...' - user's recipient address
      deadline: deadline, //Unix seconds
      amountIn: inputTinybar, //in Tinybar
      amountOutMinimum: outputAmountMin//in token's smallest unit
    };

    //encode each function individually
    const swapEncoded = abiInterfaces.encodeFunctionData('exactInput', [params]);
    const refundHBAREncoded = abiInterfaces.encodeFunctionData('refundETH');

    //multi-call parameter: bytes[]
    const multiCallParam = [swapEncoded, refundHBAREncoded];

    //get encoded data for the multicall involving both functions
    const encodedData = abiInterfaces.encodeFunctionData('multicall', [multiCallParam]);

    //get encoded data as Uint8Array
    const encodedDataAsUint8Array = hexToUint8Array(encodedData);

    const response = await new ContractExecuteTransaction()
     .setPayableAmount(Hbar.from(inputTinybar, HbarUnit.Tinybar))
     .setContractId(swapRouterContractId)
     .setGas(gasLim)
     .setFunctionParameters(encodedDataAsUint8Array)
     .execute(client);

    const record = await response.getRecord(client);
    const result = record.contractFunctionResult!;
    const values = result.getResult(['uint256']);
    const amountOut = values[0]; //uint256 amountOut
    ```
  </Tab>
</Tabs>

***

## Swap HBAR for exact tokens

Swap a maximum amount of HBAR to receive an exact tokens amount.

Solidity function name: `exactOutput`

| Struct Parameter Name | Description                                                   |
| --------------------- | ------------------------------------------------------------- |
| *bytes path*          | A bytes array representing a route path including fees data   |
| *recipient*           | EVM address of the token recipient                            |
| *deadline*            | Deadline in Unix seconds                                      |
| *amountOut*           | The exact output token amount to receive in its smallest unit |
| *amountInMaximum*     | The maximum HBAR amount to spend, in tinybar                  |

<CodeGroup>
  ```solidity ISwapRouter.sol theme={null}
  struct ExactOutputParams {
    bytes path;
    address recipient;
    uint256 deadline;
    uint256 amountOut;
    uint256 amountInMaximum;
  }

  function exactOutput(ExactOutputParams calldata params) external payable returns (uint256 amountIn);
  ```

  ```solidity SwapRouter.sol theme={null}
  /// @inheritdoc ISwapRouter
  function exactOutput(ExactOutputParams calldata params)
    external
    payable
    override
    checkDeadline(params.deadline)
    returns (uint256 amountIn)
  {
    // it's okay that the payer is fixed to msg.sender here, as they're only paying for the "final" exact output
    // swap, which happens first, and subsequent swaps are paid for within nested callback frames
    exactOutputInternal(
      params.amountOut,
      params.recipient,
      0,
      SwapCallbackData({path: params.path, payer: msg.sender})
    );

    amountIn = amountInCached;
    require(amountIn <= params.amountInMaximum, 'Too much requested');
    amountInCached = DEFAULT_AMOUNT_IN_CACHED;
  }
  ```
</CodeGroup>

<Warning>
  Ensure that the `refundETH` is included in the multicall so that any excess payable HBAR amount, up to the maximum amount, is refunded to the sender.
</Warning>

<Warning>
  Set the maximum input token amount (`amountInMaximum`) with caution.

  A low maximum might lead to a swap failure if the required liquidity surpasses this limit or due to rapid price movements. Conversely, setting it too high can expose you to significant slippage, potentially leading to a financial loss as you might spend far more tokens than expected.
</Warning>

<Tip>
  The data passed to the 'path' parameter follows this format: \[token, fee, token, fee, token, ...], but **reversed** (i.e. the first token in the array should be output token), with each 'token' in the route being 20 bytes long and each 'fee' being 3 bytes long. Example, 0x000BB8 (3000) for a 0.30% fee.
</Tip>

### Code overview

<Tabs>
  <Tab title="JavaScript SDK">
    Resources:

    * [SaucerSwap deployed contract IDs](/developers/contracts)
    * [Ethers.js docs (v6)](https://docs.ethers.org/v6/)
    * [Hedera JavaScript SDK](https://github.com/hashgraph/hedera-sdk-js)
    * [Associate tokens to an account](https://docs.hedera.com/hedera/sdks-and-apis/sdks/token-service/associate-tokens-to-an-account)

    ```typescript theme={null}
    import * as ethers from 'ethers'; //V6
    import {
      ContractExecuteTransaction,
      TokenAssociateTransaction
    } from '@hashgraph/sdk';

    //Client pre-checks:
    // - Output token is associated

    //load ABI data containing SwapRouter, PeripheryPayments and Multicall functions
    const abiInterfaces = new ethers.Interface(abi);

    //ExactOutputParams
    const params = {
      path: routeDataWithFee, //'0x...' (reversed route path)
      recipient: recipientAddress, //'0x...' - user's recipient address
      deadline: deadline, //Unix seconds
      amountOut: outputAmount, //in token's smallest unit
      amountInMaximum: inputTinybarMax //in Tinybar
    };

    //encode each function individually
    const swapEncoded = abiInterfaces.encodeFunctionData('exactOutput', [params]);
    const refundHBAREncoded = abiInterfaces.encodeFunctionData('refundETH');

    //multi-call parameter: bytes[]
    const multiCallParam = [swapEncoded, refundHBAREncoded];

    //get encoded data for the multicall involving both functions
    const encodedData = abiInterfaces.encodeFunctionData('multicall', [multiCallParam]);

    //get encoded data as Uint8Array
    const encodedDataAsUint8Array = hexToUint8Array(encodedData);

    const response = await new ContractExecuteTransaction()
     .setPayableAmount(Hbar.from(inputTinybarMax, HbarUnit.Tinybar))
     .setContractId(swapRouterContractId)
     .setGas(gasLim)
     .setFunctionParameters(encodedDataAsUint8Array)
     .execute(client);

    const record = await response.getRecord(client);
    const result = record.contractFunctionResult!;
    const values = result.getResult(['uint256']);
    const amountIn = values[0]; //uint256 amountIn
    ```
  </Tab>
</Tabs>

## Next steps

<CardGroup cols={2}>
  <Card title="Swap quote (V2)" href="/developers/v2/swap/swap-quote">
    Fetch expected amounts from QuoterV2 first.
  </Card>

  <Card title="Swap tokens for HBAR (V2)" href="/developers/v2/swap/swap-tokens-for-hbar">
    Run the same flow in the opposite direction.
  </Card>

  <Card title="Track swap events (V2)" href="/developers/v2/swap/track-swap-events">
    Monitor executed swaps in near real time.
  </Card>
</CardGroup>