一个AJAX通用的JS文件

var http_request = false;
function send_request(method, url, content, responseType, callback) {
 //window.alert("I am here");
 http_request = false;
 if (window.XMLHttpRequest) {
  http_request = new XMLHttpRequest();
  if (http_request.overrideMimeType) {
   http_request.overrideMimeType("text/xml");
  }
 } else {
  if (window.ActiveXObject) {
   try {
    http_request = new ActiveXObject("Msxml2.XMLHTTP");
   }
   catch (e) {
    try {
     http_request = new ActiveXObject("Microsoft.XMLHTTP");
    }
    catch (e) {
    }
   }
  }
 }
 if (!http_request) {
  window.alert("can not create XMLRequest");
  return false;
 }
 if (responseType.toLowerCase() == "text") {
  http_request.onreadystatechange = callback;
 } else {
  if (responseType.toLowerCase() == "xml") {
   http_request.onreadystatechange = callback;
  } else {
   window.alert("the responseType is error!");
   return false;
  }
 }

 if (method.toLowerCase() == "get") {
  http_request.open(method, url, true);
 } else {
  if (method.toLowerCase() == "post") {
   http_request.open(method, url, true);
   http_request.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
  } else {
   window.alert("the method is error!");
   return false;
  }
 }
 http_request.send(content);
}
function processTextResponse() {
 if (http_request.readyState == 4) {
  if (http_request.status == 200) {
   alert("Text is right");
  } else {
   alert("the page you request has error!");
  }
 }
}
function processXMLResponse() {
 if (http_request.readyState == 4) {
  if (http_request.status == 200) {
   alert("XML is right");
  } else {
   alert("the page you request has error!");
  }
 }
}