rewrite conversion from py to node

calculate.js

@@ -3,14 +3,16 @@ const fs = require('fs');
 
 module.exports = {
     bfx: async function() {
+        const hkdrate = 0.1287 // approximate rate
         const btcDataURL = "https://api-pub.bitfinex.com/v2/ticker/tBTCUSD"
         const response = await axios.get(btcDataURL)
         const data = response.data
             //console.log(data[6])
 
         const satDenominator = 100000000
-        const hkdrate = 0.1287 // approximate rate
+            // see docs : https://docs.bitfinex.com/reference#rest-public-ticker
         btcLastPrice = data[6]
+
         const sathkd = Math.round((1 / btcLastPrice) * satDenominator * hkdrate)
             //console.log("bitfinex last price: ", btcLastPrice, "current satHKD: ", sathkd)
         return sathkd