原生ajax

function ajax2() {
	var ajaxData = {
		type: arguments[0].type || "GET",
		url: arguments[0].url || "",
		async: arguments[0].async || "true",
		data: arguments[0].data || null,
		dataType: arguments[0].dataType || "text",
		contentType: arguments[0].contentType || "application/x-www-form-urlencoded",
		beforeSend: arguments[0].beforeSend || function () { },
		success: arguments[0].success || function () { },
		error: arguments[0].error || function () { }
	}
	ajaxData.beforeSend()
	var xhr = createxmlHttpRequest();
	xhr.responseType = ajaxData.dataType;
	xhr.open(ajaxData.type, ajaxData.url, ajaxData.async);
	xhr.setRequestHeader("Content-Type", ajaxData.contentType);
	xhr.send(convertData(ajaxData.data));
	xhr.onreadystatechange = function () {
		if (xhr.readyState == 4) {
			if (xhr.status == 200) {
				ajaxData.success(xhr.response)
			} else {
				ajaxData.error()
			}
		}
	}
}

function createxmlHttpRequest() {
	if (window.ActiveXObject) {
		return new ActiveXObject("Microsoft.XMLHTTP");
	} else if (window.XMLHttpRequest) {
		return new XMLHttpRequest();
	}
}

function convertData(data) {
	if (typeof data === 'object') {
		var convertResult = "";
		for (var c in data) {
			convertResult += c + "=" + data[c] + "&";
		}
		convertResult = convertResult.substring(0, convertResult.length - 1)
		return convertResult;
	} else {
		return data;
	}
}