function ajax(method, url, data, success) {

	var xhr = null;

	try {

		xhr = new XMLHttpRequest();

	} catch (e) {

		xhr = new ActiveXObject('Microsoft.XMLHTTP');

	}

	if (method == 'get' && data) {

		url += '?' + data;

	}

	xhr.open(method,url,true);

	if (method == 'get') {

		xhr.send();

	} else {

		xhr.setRequestHeader('content-type', 'application/x-www-form-urlencoded');

		xhr.send(data);

	}

	xhr.onreadystatechange = function() {

		if ( xhr.readyState == 4 ) {

			if ( xhr.status == 200 ) {

				success && success(xhr.responseText);

			} else {

				alert('出错了,Err：' + xhr.status);

			}

		}

	}

}