Jquery $.post returns object

Question

I am attempting to have the user enter their un/pw, click a button, have a javascript function take the un/pw entered, send it to a php script which will return a 1 or 0 based on whether the un/pw was valid.

In the javascript page I have:

function handleLogin() {
    var username = document.getElementById('un').value;
    var password = document.getElementById('pw').value;

    var valid = $.post("getLogin.php", {"un": username, "pw": password}, "json");
    alert(valid);
}

In the php file I have:

$username = $_POST['un'];
$password = $_['pw'];
$valid = 0;

# This section will open a connection to the existing backup server and get the last ith_rid used.
# It will then store that ith_rid to be used later and then close the database connection 
$mysqlconn = new mysqli('localhost','username','password','database');
if ($mysqlconn->connect_errno) {
    echo "Failed to connect to MySQL: (" . $mysqlconn->connect_errno . ") " . $mysqlconn->connect_error;
}

###################################################
## Get username and password
##################################################  
$res = $mysqlconn->query("SELECT username, password FROM table WHERE username = '" .$username . "'");
if (!$res) {                                            ##If there is an error running query, display it to the screen.
    echo "Error: $mysqlconn->error \n";
}

while($row = $res->fetch_assoc()) {
    $un = trim($row["username"]);
    $pw = trim($row["password"]);
}

if ($un == $username && $pw == $password){
    $valid = 1;
}

echo json_encode($valid);

The php does return something, but it is in an object. Not sure how to access the variable from the javascript in order to determine if it is 1 or 0.

Edit:

So I changed things up a bit and it is working correctly now.

carrierchange.js

jQuery(document).ready(function () {
    $("#content").append("<form name='loginForm' autocomplete='off'>");
    $("#content").append("<table align=center>");
    $("#content").append("<tr><td colspan=2 bgcolor=#87C9FF><center><h2>Login</h2></center></td></tr>");
    $("#content").append("<tr><td><label for='un'>Username:</label></td><td><input id='un' name='un'></td></tr>");
    $("#content").append("<tr><td><label for='pw'>Password:</label></td><td><input id='pw' name='pw' type='password'></td></tr>");
    $("#content").append("<tr><td colspan=2><center><input type='submit' class='btn' value='Login' onClick='handleLogin()'></center></td></tr>");
    $("#content").append("</table>");
    $("#content").append("</form>");
    document.getElementById('un').focus().focus();
});

function handleLogin() {
    var username = document.getElementById('un').value;
    var password = document.getElementById('pw').value;
    var valid;

    $.get("getLogin.php", {un: username, pw: password}, "json", function(data) {
        console.log(data);
    }); 
}

getLogin.php

<?php

    $username = $_GET['un'];
    $password = $_GET['pw'];
    $valid = 0;

    # This section will open a connection to the existing backup server and get the last ith_rid used.
    # It will then store that ith_rid to be used later and then close the database connection 
    $mysqlconn = new mysqli('localhost','username','password','datebase');
    if ($mysqlconn->connect_errno) {
        echo "Failed to connect to MySQL: (" . $mysqlconn->connect_errno . ") " . $mysqlconn->connect_error;
    }

    ###################################################
    ## Get username and password
    ##################################################  
    $res = $mysqlconn->query("SELECT username, password FROM cc_user WHERE username = '" .$username . "'");
    if (!$res) {                                            ##If there is an error running query, display it to the screen.
        echo "Error: $mysqlconn->error \n";
    }

    while($row = $res->fetch_assoc()) {
        $dbusername = trim($row["username"]);
        $dbpassword = trim($row["password"]);
    }

    if ($dbusername == $username){
        $valid = 1;
    }

    echo json_encode($valid);
?>

Answer 1

Since $.post is an asynchronous request, you should handle the received data in the callback function:

$.post("getLogin.php", {"un": username, "pw": password}, "json", function(data) {
    console.log(data); //received data
});