$(document).ready(function(){
    buscaCotacao(urlBuscaCotacao);
    
    function buscaCotacao(urlBusca){
	    req.open('GET', urlBusca, true);
	    req.onreadystatechange = esperaCotacao;
	    req.send(null);
	}
	
	function esperaCotacao() {
	    if(req.readyState == 4) {
	        if (req.status == 200) {
	            var jsonData = JSON.parse(req.responseText);
	            if(jsonData.length != 0){
		            document.getElementById('cotacao-dolar').innerHTML = jsonData['dolar'];
		            document.getElementById('cotacao-euro').innerHTML = jsonData['euro'];
		            document.getElementById('cotacao-petroleo').innerHTML = jsonData['petroleo'];
		        }else{
		            document.getElementById('cotacao-dolar').innerHTML = 'Off';
		            document.getElementById('cotacao-euro').innerHTML = 'Off';
		            document.getElementById('cotacao-petroleo').innerHTML = 'Off';
		        }
	        }
	    }
	}
});