NodeJS undefined value - string

Question

I can't seem to get this to work with a string
binance.prices(function(ticker) {
console.log("prices()", ticker);
console.log("Price of BNB: ", ticker.BNBBTC);
});
returns the correct value, however,
binance.prices(function(ticker) {
var tickerName = "BNBBTC";
console.log("prices()", ticker);
console.log("Price of BNB: ", ticker.tickerName);
});
returns undefined. I've asked around and haven't been able to get any help on this.

Answer 1

Solved my problem by using ticker[tickerName] instead! Thanks for the help :)

Answer 2

Of course you cannot change it like that.
They are 2 different things
1) var tickerName = "BNBBTC";
this means your variable tickerName value is a string and equal to "BNBBTC"
so ticker.tickerName will not be equal to ticker.BNBBTC (I will explain below)
That is why it return undefined because Node trying to find ticker.tickerName, which means Node trying to find the tickerName attribute from ticker. And your tickerName that you define is a variable, not an attribute of ticker
2) ticker.BNBBTC is a variable that already have a value. Remember, the part of BNBBTC is not a value, nor a string. but it is a attribute of ticker.
Look at the difference, one of them is string, one of them is an attribute to ticker.
if you want to do something like that, maybe you can approach it by using:
binance.prices(function(ticker) {
var tickerName = ticker.BNBBTC;
console.log("prices()", ticker);
console.log("Price of BNB: ", tickerName);
});
Happy Coding!
Addtional:
if you insist want to use ticker.tickerName, you can use this code:
binance.prices(function(ticker) {
var ticker.tickerName = ticker.BNBBTC; #I change this part
console.log("prices()", ticker);
console.log("Price of BNB: ", ticker.tickerName); #I change this part
});