純JavaScript實現AJAX。具體代碼如下：
    window.lcq = {};
    (function(obj) {
    obj = {};
    //創(chuàng)建xmlhttprequest對象
    obj.createXMLHttpRequest = function() { if (window.ActiveXObject) { var aVersions = ["MSXML2.XMLHttp.5.0", "MSXML2.XMLHttp.4.0", "MSXML2.XMLHttp.3.0", "MSXML2.XMLHttp", "Microsoft.XMLHttp"]; for (var i = 0; i < aVersions.length; i++) { try { return new ActiveXObject(aVersions[i]); } catch (oError) { continue; } } } else if (window.XMLHttpRequest) { return new XMLHttpRequest(); } throw new Error("XMLHttp object could not be created."); }
    //ajax
    obj._xmlHttp = null;
    obj.ajax = function(options) {
    try {
    obj._xmlHttp = this.createXMLHttpRequest();
    obj._xmlHttp.open(options.method, options.url, true);
    obj._xmlHttp.setRequestHeader("cache-control", "no-cache");
    obj._xmlHttp.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
    obj._xmlHttp.onreadystatechange = function() {
    if (obj._xmlHttp.readyState == 4) {
    if (obj._xmlHttp.status == 200) {
    var _response = "";
    switch (options.dataType.toLowerCase()) {
    case "json":
    _response = eval(obj._xmlHttp.responseText);
    break;
    case "xml":
    _response = obj._xmlHttp.responseXML;
    break;
    case "html":
    _response = obj._xmlHttp.responseText;
    break;
    default:
    _response = obj._xmlHttp.responseText;
    break;
    }
    options.success(_response);
    }
    }
    else { }
    }
    obj._xmlHttp.send(options.data);
    }
    catch (e) { }
    }
    //提示信息的方法
    obj.show = function(message) { alert(message); }
    //對象引用
    lcq = obj;
    $ = obj;
    })(lcq);
    //簡單的用法
    function _testAjax(obj) {
    obj.disabled = true;
    obj.value = "正在提交......";
    $.ajax({ url: "/xmls/url.xml",
    method: "GET",
    data: "",
    dataType: "html",
    success: function(response) {
    obj.disabled = false;
    obj.value = "處理完畢";
    //show(response);
    },
    error: function(response) { alert(response); }
    });
    }
    function show(message) {document.getElementById("wraper").innerHTML = message;}
    //html部分
    <div id="wraper">
    </div>
    <input type="button" value="Ajax測試" onclick="_testAjax(this);" />