PHP实战：PHP实现简单ajax Loading加载功能示例

var xmlHttp;
function createXmlHttpReq() {
  if(window.ActiveXObject) {
    xmlHttp = new ActiveXObject('Microsoft.XMLHTTP');
  } else if(window.XMLHttpRequest) {
    xmlHttp = new XMLHttpRequest();
  }
}
function funMy(url) {
  createXmlHttpReq();
  try {
    xmlHttp.onreadystatechange = cb;//一定要在open()前,下边会有说明.在此处犯错了
    xmlHttp.open("GET","for.php?id="+url,true);
    xmlHttp.send(null);
  } catch(e) {
    alert("您访问的资源不存在");
  }
}
//回调函数
function cb() {
  if(xmlHttp.readyState==1) {
    alert("1-------------->");
    //在Google Chrome 浏览器里不显示loading图片,三秒后显示内容,问题已解决,下边有说明
    document.getElementById('ajax').innerHTML = "<img src=loading2.gif>";
    //document.getElementById('ajax').innerHTML = "Loading......";
  }
  if(xmlHttp.readyState == 4 && xmlHttp.status == 200) {
      var data = xmlHttp.responseText;
      document.getElementById('ajax').innerHTML = data;
  }
}