currency value with react native

I'm trying to create a currency conversion app, the user needs to enter a value like "120" and the app will do the conversion.

the result should look like this:$ 129.189,12

but it’s getting like this: 129189.12

my function:

currencyBrToAr = () => {        const real = 17.90;        const v = this.state.coinValue;        let result = this.state.resultValue;        const type = this.state.currencyCoin;        result = v * real;        this.setState({             showMessage: true,             resultValue: result,        });    }