GETの時
xhr.open('GET',encodeURIComponent('sample.sample?query1=some2&query2=some2'))
xhr.send(null)

POSTのとき
xhr.open('POST', 'sample.sample')
xhr.setRequestHeader('content-type','application/x-www-urlecoded;charset=UTF-8');
xhr.send(encodeURIComponent('query1=some1&query2=some2'))