How to use ajax to create an XMLHttpRequest object_Basic knowledge

try
{
// Firefox, Opera 8.0, Safari
xmlHttp=new XMLHttpRequest();
}
catch (e)
Explorer
try
{
xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
}
catch (e)
xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
　}
　catch (e)
　{
　alert("Your browser does not support AJAX!");
　}
　}
　}
　}
　
　

　 User:
Time:
　

　


First declare an xmlHttp variable that holds the XMLHttpRequest object.
Then use XMLHttp=new XMLHttpRequest() to create this object. This statement is specific to Firefox, Opera, and Safari browsers. If that fails, try xmlHttp=new ActiveXObject("Msxml2.XMLHTTP") for Internet Explorer 6.0, and if that also fails, try xmlHttp=new ActiveXObject("Microsoft.XMLHTTP") for Internet Explorer 5.5.

If none of these three methods work, the user is using an outdated browser and he or she will see a prompt stating that the browser does not support AJAX.

You don’t have to go through so much trouble. You can directly save the definition of this function as a separate js file and reference this file in the page that needs to use AJAX.
As detailed below:
JScript code:

{
try
{
xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
}
catch (e)
{
xmlhttp = false;
}
}
if (!xmlhttp && typeof XMLHttpRequest!='undefined')
{
try
{
xmlhttp = new XMLHttpRequest();
}
catch (e)
{
xmlhttp=false;
}
}
if (!xmlhttp && window.createRequest)
{
try
{
xmlhttp = window.createRequest();
}
catch (e)
{
xmlhttp=false;
}
}
return xmlhttp;


} Define the above function and create an instance when calling it, as follows:
JScript code:




Copy code

You can also use jquery directly to do it in one sentence, as follows:




Copy the code

$(document).ready(function(){
$("#userpass").blur(function(){
var password=$("#userpass").val( );
var name=$("#username").val();
if(password==""||password==null){
$("#pass").html ("Please enter your password! ");
b=false;
}else if(!/^[a-zA-Z0-9_] {6,16}$/.test(password)){
$("#pass").html("The input format is incorrect! The password should be at least 6 digits or Characters");
b=false;
}else{
$.get("LoginAjaxPassword",{"userpass":encodeURI(encodeURI(password)),"username": encodeURI(encodeURI(name))},function(response){
$("#pass").html(response);
if(response=="" "√" ""){
b=true;
}
});
}
return b;
});
$("#login-submit").click(function(){
var autologin=document.getElementById("autologin").checked;
if(a&&b){
//if ($("#autologin").attr("checked")==true){
if(autologin==true){
//${"#login-user-form"}.attr( "action","AutoLogin");
//$("#login-user-form").submit();
document.form.action="AutoLogin";
document.form. submit();
}else{
//${"#login-user-form"}.attr("action","Login");
//$("#login-user -form").submit();
document.form.action="Login";
document.form.submit();
}
} else{}
});
});