(JS/JQ)与Ajax

JS与Ajax(异步JS和XML):

1.XMLHttpRequest对象的常用方法：

open()准备请求   send()传送请求   abort()取消请求

readyState(请求状态码):0(未开始)、1(开启)、2(已传送)、3(接收中)、4(已载入) 

status(HTTP请求状态码):404(找不到文件)、200(OK)

onreadystatechange:请求状态改变时会被调用函数引用

responseText:服务器返回的纯文本字符串

responseXML:服务器返回的xml格式对象

2.创建请求对象 function createRequest()

function createRequest() {
  try {
    request = new XMLHttpRequest();
  } catch (tryMS) {
    try {
      request = new ActiveXObject("Msxml2.XMLHTTP");
    } catch (otherMS) {
      try {
        request = new ActiveXObject("Microsoft.XMLHTTP");  //针对IE浏览器
      } catch (failed) {
        request = null;
      }
    }
  }
  return request;
}

得到请求对象：request = createRequest();

设置请求路径与请求数据：var url = "register.php";
                                  var requestData = "username=" + escape(document.getElementById("username").value);  //POST请求

配置请求：request.open("GET/POST",url,true(异步)/false(同步：不需要回调函数))

配置回调函数：request.onreadystatechange = displayDetails;

设置请求首部：request.setRequestHeader("Content-Type", "application/x-www-form-urlencoded"); //POST请求

发送请求：request.send(null); //GET请求

              request.send(requestData); //POST请求

创建回调函数：function displayDetails()

例：

function displayDetails() {
  if ((request.readyState == 4) || (request.status == 200) ){
      detailDiv = document.getElementById("description");
      detailDiv.innerHTML = request.responseText;
  }
}

 JQ与Ajax:

1.$.get(URL,callback);

例：$.get("url", function(data) { alert(”data“) });

2.$.post(URL,data,callback);

例：$.post("url", { max: 'jq', name: 'eezz' }, function(data) { alert(“data”) });

3.$.ajax

jQuery.ajax({
                type: "POST",
                url: "url",
                data: "max=jq &name=eezz",
                dataType: "json",
                success: function(msg) {alert(msg);}
});
$.ajax方法参数详解：http://blog.sina.com.cn/s/blog_4f925fc30100la36.html