var SumField, fromTypeField, convertBtn, ratesRequest;

function init() 
{
        SumField = document.getElementById("sum");
        fromTypeField = document.getElementById("from_type");
        convertBtn = document.getElementById("convert");
        
        convertBtn.onclick = getRates;
}

function convertMoney()
{
        var rates = new Array(), sum;
        document.getElementById("result").innerHTML = '';
        if (ratesRequest.readyState == 4)
        {
                rates = ratesRequest.responseJS;
                raw_sum = SumField.value.replace(',','.');
                sum = parseFloat(raw_sum);
                converted_sum = sum*rates[fromTypeField.value] + (sum*rates[fromTypeField.value])*2/100;
                if (converted_sum.toFixed)
                        converted_sum = converted_sum.toFixed(2);
                
                document.getElementById("result").innerHTML = isNaN(converted_sum)?"0.00":converted_sum;
        }
}

function getRates()
{
        ratesRequest = new JsHttpRequest();
        ratesRequest.onreadystatechange = convertMoney;
        ratesRequest.open( 'GET', 'getrates.php', true);
        ratesRequest.send({action: 'get_rates'});
}
window.onload = init;