将数据从$ .ajax发送到php

I am trying to send the username to php using ajax.

Here is my js.

$('#username').blur(function(){
    var username = $("#username").val();
    $.ajax({
        type: "POST",
        url: "dbquery.php",
        data: username,
        success: function(result){
            $("#dbdata").html(result);
        }
    });
});

And here is php.

$value = $_GET['username'];

I know it is about the ajax because everything worked fine when the ajax part was written in pure javascript.

Send data as an object as $_GET reads associative array of variables passed to the current script via the URL parameters

data: {username:username},

You are using type:"POST" and trying to retrieve the values in GET Array in the PHP code .Change the method to GET

$('#username').blur(function(){
    var username = $("#username").val();
    $.ajax({
        type: "GET",
        url: "dbquery.php",
        data: username,
        success: function(result){
            $("#dbdata").html(result);
        }
    });
});

Use below code

$('#username').blur(function(){
    var username = $("#username").val();
var dataString = 'username ='+ encodeURIComponent(username) ;
    $.ajax({
        type: "POST",
        url: "dbquery.php",
        data: dataString ,
        success: function(result){
            $("#dbdata").html(result);
        }
    });
});

First: You are using POST in ajax. and GET in PHP, which is wrong.

If we use POST then in the PHP file, we use $_POST[”] to get the value. If we use GET then we use $_GET[]

Second: data is passed as an object as data: {username: username}. This means that if we use $_POST[‘username’] in the PHP file, we will get the value of the username. Your final code will be

AJAX

$('#username').blur(function(){
    var username = $("#username").val();
    $.ajax({
        type: "POST",
        url: "dbquery.php",
        data: {username:username},
        success: function(result){
            $("#dbdata").html(result);
        }
    });
});

PHP

$value = $_POST['username']

Please pass data as an Object. To access data in PHP you have to use $_POST['username'], $_POST['password'] etc

    $('#username').blur(function(){
        var data = {
            username:$("#username").val(),
            password: $("#password").val()
        };
        $.ajax({
            type: "POST",
            url: "dbquery.php",
            data: data,
            success: function(result){
                $("#dbdata").html(result);
            }
        });
    })

first of all your ajax type is post but you getting value using GET[] This is mistake here.

try this

$('#username').blur(function(){
var username = $("#username").val();
$.ajax({
    type: "POST",
    url: "dbquery.php",
    data: {'username':username},
    success: function(result){
        $("#dbdata").html(result);
    }
}); });  

and you have to use this to get value

$value = $_POST['username'];