Money. 
Simple JavaScript currency conversion library with no dependencies.
Install
go get -u github.com/hashcott/money.go
You’ll need to do one more thing before you can use it, which is:
Setting up exchange rates with rates
To use money.go to convert currencies, you’ll need to feed it with some exchange rate data and provide a base currency. (As long as you have exchange rates for every currency relative to one single other (‘base’) currency, money.go can convert between any other two)
The library doesn’t specify a format for currency names/codes (we recommend sticking to the standard three-letter codes). It also does not mind how accurate they are, or which currency is your base rate.
They should like this:
NewExchanger(base CurrencyCode, rates Rates)
package main
import (
moneygo "github.com/hashcott/money.go"
)
func main() {
fx := moneygo.NewExchanger(moneygo.USD, moneygo.Rates{"USD": 1, "EUR": 0.745101, "GBP": 0.647710,
"HKD": 7.781919})
}
.Convert(val float64)
The basic function of the library – converts a value from one currency to another. Uses the default from and to currencies in fx.DefaultSettings:
fx.DefaultSettings = moneygo.FromTo{From: moneygo.USD, To: moneygo.GBP}
val, err := fx.Convert(1000); // convert from USD to GBP
.ConvertWithFromTo(val float64, fromTo FromTo)
fx.ConvertWithFromTo(1000, moneygo.FromTo{From: moneygo.USD, To: moneygo.GBP})
