Trade Previews

import { DumpsterClient } from '@dumpster-cash/dumpster-sdk';

const client = new DumpsterClient(connection);

Curve buy preview

Start here when the user enters a GOR spend amount.

import BN from 'bn.js';

const preview = client.preview.curveBuy({
  feeConfig,
  bondingCurve,
  amountInGor: new BN(1_000_000_000),
});

Key fields:

• preview.amountOutTokens -> token output after fees
• preview.fees.feeAmountGor -> fee amount charged on the trade
• preview.priceImpactBps -> how far the execution moves from the pre-trade spot price
• preview.postTradeReserves -> the next virtual reserve state if the trade lands

Curve buy preview by target output

Choose this path when the target token output is known and the missing number is the required GOR input.

const preview = client.preview.curveBuyExactOut({
  feeConfig,
  bondingCurve,
  amountOutTokens: new BN(25_000_000_000),
});

Key fields:

• preview.amountInGor -> total GOR input required
• preview.amountInNetGor -> GOR that actually reaches the curve after fees
• preview.amountOutTokens -> exact token output being targeted

Curve sell preview

Start here when the user enters a token amount to sell.

const preview = client.preview.curveSell({
  feeConfig,
  bondingCurve,
  amountInTokens: new BN(25_000_000_000),
});

Key fields:

• preview.amountOutGorGross -> output before fees
• preview.amountOutGorNet -> output after fees
• preview.fees.feeAmountGor -> fee amount charged on the trade

AMM buy preview

This preview answers the exact-output AMM buy question: how much quote does this output actually cost?

const preview = client.preview.swapBuy({
  feeConfig,
  pool,
  baseReserves,
  quoteReserves,
  baseMintSupply,
  baseAmountOut: new BN(5_000_000_000),
});

Key fields:

• preview.quoteAmountForSwap -> quote amount consumed by the pool before fees
• preview.quoteAmountInTotal -> total spend including fees
• preview.fees.totalFeeAmount -> total fee charged on the quote side

AMM buy preview by total quote input

This preview answers the exact-input AMM buy question: how much base output fits inside a total quote budget?

const preview = client.preview.swapBuyExactIn({
  feeConfig,
  pool,
  baseReserves,
  quoteReserves,
  baseMintSupply,
  quoteAmountInTotal: new BN(1_000_000_000),
});

Key fields:

• preview.baseAmountOut -> token output that fits inside the total quote budget
• preview.quoteAmountInTotal -> total quote input used for the preview
• preview.fees.totalFeeAmount -> total fee charged on the quote side
• preview.priceImpactBps -> market movement implied by that spend

AMM sell preview

Start here when the sell size is known up front.

const preview = client.preview.swapSell({
  feeConfig,
  pool,
  baseReserves,
  quoteReserves,
  baseMintSupply,
  baseAmountIn: new BN(5_000_000_000),
});

Key fields:

• preview.quoteAmountOutGross -> quote output before fees
• preview.quoteAmountOutNet -> final output after fees
• preview.priceImpactBps -> execution movement vs the pre-trade spot price

When the math helpers still make sense

The raw math helpers still exist for simulations, tests, and analytics. For quoting and transaction building, the preview surface is usually better because it keeps amounts, fees, impact, and post-trade state together.