Node js API wrapper for altcoin exchange

Question

I'm trying to make a simple market maker bot and i need to use the variables bid, ask and spread in other functions to calculate what kind of buy/sell orders to create. How would i pass these variables along? Also how come i'm able to subtract (ask - bid) and not add like (bid + 0.001)

NPM poloniex.js

    function getSpread() {

    poloniex.getTicker(function(err, data){
    if (err){
        console.log('ERROR', err);
        return;
    }

    var ask = data.BTC_LTC.lowestAsk;
    var bid = data.BTC_LTC.highestBid;
    var spread = ((ask - bid) / ask);

    console.log('Ask:', ask,'Bid:', bid,'Spread:', spread); 

    });
}

Answer 1

In order to pass these variables to a separate function, you may do something like this -

var calculateOrder = function (bid, ask, spread) {
    // Use variables
}

function getSpread() {
    poloniex.getTicker(function(err, data) {
        if (err){
            console.log('ERROR', err);
            return;
        }

        var ask = data.BTC_LTC.lowestAsk;
        var bid = data.BTC_LTC.highestBid;
        var spread = ((ask - bid) / ask);

        calculateOrder(bid, ask, spread);

    });
}

You should always convert lowestAsk and highestBid to numbers before doing mathematical operations on them

var ask = Number(data.BTC_LTC.lowestAsk);
var bid = Number(data.BTC_LTC.highestBid);