HumbleSDK

A Javascript SDK for interaction with the HumbleSwap DEx

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A Javascript library for interacting with the HumbleSwap DEx.
Methods are listed below, along with usage examples where possible.
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Swapping

Swapping utility functions.

calculatePriceImpact

function calculatePriceImpact(amtA: string | number, opts: SwapTxnOpts): string | 0;

Compares the size of expected swap output to the size of an “ideal” output.
Price impact computes

  • the output if the pool was (hypothetically) “perfectly balanced”
  • the expected output of a swap with the pool’s current state

and compares the two.
So e.g. if calculatePriceImpact(x, { ... }) returns 20, it means that trade will result in 20% less value than if the pool was balanced by (e.g.) more liquidity.

calculatePriceImpact Example

See Perform Swap for usage.

calculatePriceImpact Parameters

  • amtA: string | number input amount (can represent amount for token A or B)
  • opts: SwapTxnOpts

calculatePriceImpact Returns

  • string Price impact value as a string. Value is a percentage (so e.g. 5 === 5%)

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calculateTokenSwap

function calculateTokenSwap(opts: SwapTxnOpts): SwapInfo

Calculates how much you should expect from a swap, based on the amount put in and the state of the pool.

calculateTokenSwap Example

See Perform Swap for usage.

calculateTokenSwap Parameters

calculateTokenSwap Returns

  • SwapInfo
    An object with your input amount and expected outputs. You can use this object to perform a swap transaction.

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performSwap

Renamed to Swap Tokens

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swapTokens

function swapTokens(acct: ReachAccount, opts: SwapTxnOpts): Promise<TransactionResult>

Swap one token in a Liquidity Pool for another.

swapTokens Example: Swap

See fetchLiquidityPool or subscribeToPoolStream for pool sources.

const pool = /* pool source */

// Calculate expected swap output
const { tokenAId, tokenBId } = pool;
const amountA = 100
const swap = calculateTokenSwap({ 
    pool, 
    swap: { amountA, tokenAId, tokenBId } 
});

// Perform swap
const swapOpts = { poolAddress: pool.poolAddress, swap, pool };
const { data, message, succeeded } = await swapTokens(acc, swapOpts);
// if (succeeded) data == { amountIn: string; amountOut: string }

swapTokens Example: Price Impact

(Optional) Calculate price impact to ensure the best price. Price impact is inversely proportional to expected swap output. In other words, the higher the price impact, the smaller the swap output.

💡 Why would I need this?
Because, simply, Higher impact === lower trade quality.
A very high value returned by calculatePriceImpact might be because of low pool liquidity. The HumbleSwap UI flags trades that with a >5% trade impact.

This is only included for illustration. Price impact calculation is separate from swapping, and doesn’t affect it unless you make it do so.

const pool = /* pool source */
const { tokenAId, tokenBId } = pool;
const amountA = 100
const calcOpts = { pool, swap: { amountA, tokenAId, tokenBId } };
const impact = calculatePriceImpact(amountA, calcOpts);
console.log(impact); //  "3.04"

swapTokens Parameters

swapTokens Returns

  • TransactionResult
    where data = { amountIn: string; amountOut: string } when successful

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