Why do i get minus function error in cloud function node js?

I use bignumber in nodejs for cloud functions with firebase.I added BigNumber at the end thinking that it might help.

const BigNumber = require("bignumber.js").BigNumber;
let Price = new BigNumber(0);
let Fee = new BigNumber(0.15);
let FeePrice = new BigNumber(0);
let TotalPrice = new BigNumber(0);
const priceValue = json["value"];
Price = new BigNumber(priceValue);
FeePrice = Price.times(Fee).toFormat(2, 6);
TotalPrice = Price.minus(FeePrice);

I get this error in Cloud Function Log TypeError:

Price.minus is not a function

Answer

Your typeof Price might be a string. So it needs to be converted to BigNumber. You can use TotalPrice with BigNumber static method itself. (thanks to your comment replies)

TotalPrice = new BigNumber(Price).minus(FeePrice);