Buy DEX Tokens

Buys an exact amount of tokens from the DEX orderbook.

Usage

import { client } from './viem.config'
 
const { receipt } = await client.dex.buySync({
  amountOut: 100000000n,
  maxAmountIn: 150000000n,
  tokenIn: '0x20c0000000000000000000000000000000000000',
  tokenOut: '0x20c0000000000000000000000000000000000001',
})
 
console.log('Transaction hash:', receipt.transactionHash)
Transaction hash: 0x1234567890abcdef1234567890abcdef1234567890abcdef1234567890abcdef

import { Account, Client } from 'viem/tempo'
 
export const client = Client.create({
  account: Account.fromSecp256k1('0x...'),
})

Recipes

Derive the Slippage Bound from a Fresh Quote

Combine dex.getBuyQuote with dex.buySync to derive maxAmountIn from the live price instead of guessing a limit.

import { client } from './viem.config'
 
const alphaUsd = '0x20c0000000000000000000000000000000000001'
const pathUsd = '0x20c0000000000000000000000000000000000000'
 
const invoice = 250_000000n
 
const quote = await client.dex.getBuyQuote({
  amountOut: invoice,
  tokenIn: pathUsd,
  tokenOut: alphaUsd,
})
 
const { receipt } = await client.dex.buySync({
  amountOut: invoice,
  maxAmountIn: (quote * 1_005n) / 1_000n,
  tokenIn: pathUsd,
  tokenOut: alphaUsd,
})

import { Account, Client } from 'viem/tempo'
 
export const client = Client.create({
  account: Account.fromSecp256k1('0x...'),
})

The bound above tolerates 0.5% of price movement between the quote and the swap. The buy reverts instead of overpaying if the price moves further.

Pay an Invoice in a Stablecoin You Don't Hold

Batch the buy with dex.withdraw and token.transfer to convert, withdraw, and pay an exact invoice in one atomic transaction.

import { Actions } from 'viem/tempo'
import { client } from './viem.config'
 
const alphaUsd = '0x20c0000000000000000000000000000000000001'
const pathUsd = '0x20c0000000000000000000000000000000000000'
 
const invoice = 250_000000n
 
const receipt = await client.transaction.sendSync({
  calls: [
    Actions.dex.buy.call({
      amountOut: invoice,
      maxAmountIn: 251_000000n,
      tokenIn: pathUsd,
      tokenOut: alphaUsd,
    }),
    Actions.dex.withdraw.call({ amount: invoice, token: alphaUsd }),
    Actions.token.transfer.call({
      amount: invoice,
      to: '0x742d35Cc6634C0532925a3b844Bc9e7595f0bEbb',
      token: alphaUsd,
    }),
  ],
})

import { Account, Client } from 'viem/tempo'
 
export const client = Client.create({
  account: Account.fromSecp256k1('0x...'),
})

Return Value

type ReturnType = {
  /** Transaction receipt. */
  receipt: TransactionReceipt
}

The transaction receipt for the buy.

Parameters

amountOut

• Type: bigint

Amount of tokenOut to buy.

maxAmountIn

• Type: bigint

Maximum amount of tokenIn to spend.

tokenIn

• Type: Address | bigint

Token to spend: a TIP-20 token id or a contract address.

tokenOut

• Type: Address | bigint

Token to buy: a TIP-20 token id or a contract address.

account (optional)

• Type: Account | Address

Account that will be used to send the transaction.

feePayer (optional)

• Type: Account | boolean

Fee payer for the transaction (TIP-1 gas sponsorship).

Pass true to defer the fee token to an external fee payer (e.g. a relay), or a local Account to co-sign the transaction as the fee payer.

feeToken (optional)

• Type: Address | bigint

Fee token for the transaction.

Can be an unpaused USD-denominated TIP-20 token address or ID.

gas (optional)

• Type: bigint

Gas limit for the transaction.

keyAuthorization (optional)

• Type: KeyAuthorization

Signed key authorization to include with the transaction, authorizing an access key to act for the sending account.

maxFeePerGas (optional)

• Type: bigint

Max fee per gas for the transaction.

maxPriorityFeePerGas (optional)

• Type: bigint

Max priority fee per gas for the transaction.

nonce (optional)

• Type: number

Nonce for the transaction.

nonceKey (optional)

• Type: 'expiring' | 'random' | bigint

Nonce key for the transaction (TIP-1009 2D nonces).

Use 'expiring' to select an expiring nonce, which enables concurrent transaction submission without nonce ordering. Use 'random' to select a random key.

throwOnReceiptRevert (optional)

• Type: boolean
• Default: true

Whether a Sync action throws when the receipt reports a revert.

validAfter (optional)

• Type: number

Unix timestamp after which the transaction can be included.

validBefore (optional)

• Type: number

Unix timestamp before which the transaction must be included.