Ajax入门的例子

//创建xmlhttprequest对象

function createXMLHttpRequest() {
        var xmlHttp;
        if (window.ActiveXObject) {
            xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
        } else {
            xmlHttp = new XMLHttpRequest();
        }
        return xmlHttp;

    }

一个发送GET请求的例子

  

 function selected() {
        var xmlHttp;    
        var compid = document.getElementById("company_name").value;
        if (compid == null) {
            //return  false;
        }
      
        xmlHttp = createXMLHttpRequest();
        
        xmlHttp.onreadystatechange = processor;
        //alert(compid+"compid");
        xmlHttp.open("GET", "/jbbs/GetProduct?compid=" + compid, true);
        xmlHttp.send(null);
        //alert("has product");
        function processor() {
            var result,str;
            var array=[];
            //alert("begin processor");
            if (xmlHttp.readyState == 4) {
                if (xmlHttp.status == 200) {
                    /**result = xmlHttp.responseXML.getElementsByTagName("product");**/
                    result=xmlHttp.responseText;
                    var myobj = eval(result);
                    for(var i=0;i<myobj.length;i++){
                        var prod_id=myobj[i].prod_id;
                        var prod_name=myobj[i].prod_name;
                        array.push({value: prod_id, text: prod_name});
                    }
                    //alert(myobj[0].prod_id+myobj[0].prod_name);
                        //如果页面上存在这个容器，先删掉
                    var container=document.getElementById("product_container");
                    
                    while(container.hasChildNodes()){
                         container.removeChild(container.firstChild);
                    }
                    $.sexyCombo.create({
                          id : "product_name",
                          name: "product_name",
                          container: "#product_container",
                          emptyText: "--请选择名称--",
                          data:array,
                          triggerSelected: false
                    });
                    var prod=document.getElementById("product_name");
                    prod.onchange=product_selected;
                    document.getElementById("company_name__sexyCombo").onclick=company_name__sexyCombo_click;
                    document.getElementById("temp_compid").value=compid;
                }
            }

        }
    }