----------------------原始的ajax:
?function guo() {
??????????? var xhr
??????????? if (XMLHttpRequest) {
??????????????? xhr = new XMLHttpRequest();
??????????? }
??????????? else {
??????????????? xhr = ActiveXObject("XMLHttpRequest");
??????????? }
??????????? //ie5 和ie6是activeobject;
??????????? //請求方式，地址，是否異步；
??????????? xhr.open("get", "../Handler/test.ashx", true);
??????????? //發送請求
??????????? xhr.send();
???????????? //readystate:0未初始化；1，已打開，2，已發送，3正在接受，4，已加載
??????????? xhr.onreadystatechange = function (data) {
??????????????? if (xhr.readyState == 4) {
??????????????????? alert(xhr.responseText);
??????????????? }
??????????? };
??????? }
--------post方式
?function guo() {
??????????? var xhr
??????????? if (XMLHttpRequest) {
??????????????? xhr = new XMLHttpRequest();
??????????? }
??????????? else {
??????????????? xhr = ActiveXObject("XMLHttpRequest");
??????????? }
??????????? //ie5 和ie6是activeobject;
??????????? //請求方式，地址，是否異步；
??????????? //xhr.open("get", "../Handler/test.ashx", true);
??????????? xhr.open("post", "../Handler/test.ashx", true);
??????????? //發送請求
??????????? //設置請求的頭部；
??????????? xhr.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
??????????? //xhr.send();
??????????? xhr.send("a=3&b=4");
??????????? xhr.onreadystatechange = function (data) {
??????????????? if (xhr.readyState == 4) {
??????????????????? alert(xhr.responseText);
??????????????? }
??????????? };
??????? }

最初的ajax案例