JSFiddle - React, Tailwind, and code Playground

JavaScript

Request.exchange = new Class({
   
    Extends: Request.JSONP,
    
    options: {
        url: 'http://rate-exchange.appspot.com/currency?from={from}&to={to}&q={amount}',
        amount: 1
    },
        
    initialize: function(options){
        this.setOptions(options);
        this.options.url = this.options.url.substitute(this.options);
        this.parent();
    }
    
});

new Request.exchange({
    from: 'GBP',
    to: 'JPY',
    amount: '100',
    onSuccess: function(response) {
        console.log(response, response.rate, response.v);
    }
}).send();