Example Swap -> AMM Model of Uniswap

example_amm.js

/**
Example Swap -> AMM Model of Uniswap V1,V2
**/

// Testing online
// https://jsfiddle.net/itoonx/xqah6e9v/



const asset = 'BNB'
const quote = 'XRP'

const LiquidityPool = {
  BNB: 10,
  XRP: 500,
}

console.log('Init Liquidity Pool', LiquidityPool)

function addLiquidity (token, tAmount) {
  LiquidityPool[token] += tAmount
  return LiquidityPool[token]
}

function takeLiquidity (token, tAmount) {
  if (tAmount >= LiquidityPool[token]) {
    LiquidityPool[token] -= tAmount
    return LiquidityPool[token]
  } else {
    return new Error('No Liquidity')
  }
}

function swapAndLiquify (tokenA, tokenB, tAmount) {
  try {
    console.log('LiquidityPool[tokenA]', LiquidityPool[tokenA])
    console.log('LiquidityPool[tokenB]', LiquidityPool[tokenB])

    let kWeight = LiquidityPool[tokenA] * LiquidityPool[tokenB]
    console.log('kWeight', kWeight)

    addLiquidity(tokenA, tAmount) // add 10 BNB to Pool
    
    console.log('LiquidityPool[tokenA]', LiquidityPool[tokenA])
    console.log('LiquidityPool[tokenB]', LiquidityPool[tokenB])
    
    const allocP = kWeight / LiquidityPool[tokenA]
    const tReceive =  LiquidityPool[tokenB] - allocP
    console.log('tReceive', tReceive, tokenB)

    /* const pRate = tReceive / tAmount
    console.log('pRate', pRate) */

    takeLiquidity(tokenB, tReceive)
    return tReceive
  } catch (error) {
    return new Error('Error', error)
  }
}

let trades1 = swapAndLiquify('BNB', 'XRP', 1)
console.log('SWAP', trades1)

/* let trades2 = swapAndLiquify('BNB', 'XRP', 100)
console.log('SWAP', trades2)

let trades3 = swapAndLiquify('XRP', 'BNB', 50)
console.log('SWAP', trades3) */