function sendData(_data) {
	request.open("POST", [your URL], true);
	request.onreadystatechange = function() {
		if (request.readyState ==  4 ) {
			_message = request.responseText;
			if (_message == "ok") { [your code] }
			else { [your code] }
		}
	};
	request.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
	request.send(urlEncodeData(_data));
}
function urlEncodeData(data) {
	var query = [];
	if (data instanceof Object) {
		for (var i in data) query.push(encodeURIComponent(i) + "=" + encodeURIComponent(data[i]));
		return query.join('&');
	} else return encodeURIComponent(data);
}

var data = [];
var element = document.getElementByID(id_of_select);
for (var i in element.options)
	data[element.options[i].value] = element.options[i].text;
sendData(data);