test.js

et orderbookBUY = [
  [1, 0.1],
  [2, 0.2],
  [3, 0.25],
  [4, 0.15],
  [5, 0.4]
];

let orderbookSELL = [
  [5, 0.1],
  [4, 0.2],
  [3, 0.25],
  [2, 0.15],
  [1, 0.4]
];


let toBUYamount  = 0.56;
let toSELLamount = 10;

let toBUYprice   = 10;
let toSELLprice  = 10;

let LESS = 0.1;

function Feetaker(rate, fee)
{
  return rate*(1+fee);
}
function buyAmount2(orderbook, amount, min, fee) {
  let result = {
    "orders": [],
    // "amount": amount,
    "left": amount
  };
  let i = 0;
  let left = amount;
  let orders = [];
  let tempamount = 0;
  if (amount >= min) {
      while(i < orderbook.length) {
        tempamount = tempamount + orderbook[i][1]
        if(tempamount >= min){
          if(left > tempamount) {
            left -= tempamount;
            if (left < min) {
              tempamount=tempamount-(min-left);
              left=min;
            }
            result.orders.push({"rate": Feetaker(orderbook[i][0]), "amount": tempamount});
            tempamount = 0;
        }
        else {
          result.orders.push({"rate":Feetaker(orderbook[i][0]), "amount":left});
          left=0;
          break;
        }
      }
    i++;
  }
  result.left = left;
}
  console.log(result);
}



function buyPrice2(orderbook, price, min) {
  let result = {
    orders: [/*****************/],
    // price: price,
    left: price
  };
  let i = 0;
  let left = price;
  let orders = [];
  let tempamount = 0;
  if (price >= min) {
      while(i < orderbook.length) {
        tempamount = tempamount + Feetaker(orderbook[i][1]);
        if(tempamount >= min){
          if(left > tempamount*Feetaker(orderbook[i][0])) {
            left -= tempamount*Feetaker(orderbook[i][0]);
            if ((left/Feetaker(orderbook[i+1][0]) < min)&&(min-left/Feetaker(orderbook[i+1][0]>0)){
              tempamount=tempamount-(min-left/Feetaker(orderbook[i+1][0]));
              left=min*Feetaker(orderbook[i+1][0]);
            }
            result.orders.push({rate: Feetaker(orderbook[i][0]), ammount: tempamount});
            tempamount = 0;
        }
        else {
          result.orders.push({rate:Feetaker(orderbook[i][0]), ammount: left});
          break;
        }
      }
    i++;
  }
  result.left = left;
  }
  console.log(result);
}

buyAmount2(orderbookBUY, toBUYamount, LESS)