Ajax呼叫完成表格

I have a form that a user completes. after the user is done he clicks submit, the script runs and does some fancy things and returns to finished.php. on this page I have the results of his $_POST from the form....on this new page load, I need to fire an ajax call to get the data based on his $_POST result..

in layman's code:

$_POST['someValue'] = "12345";

$(document).on("pageinit","users/userInfo.php",function(){
    $.ajax({
        type: "POST",
        data:"someValue="+$_POST['someValue'],
        success: function(msg){
            $('#mainBody').html(msg);
        }
    });
});

<div id='mainBody'> --Print results of ajax call---</div>

how would i go about this

edited new code:

<script>
    $(document).on("pageinit",function(){
        $.ajax({
            type: "POST",
            url: "users/userInfo.php",
            dataType: "html",
            data:"someValue=+<?php echo $_POST['someValue'];?>",
            success: function(msg){
                alert('hi');
                $('#mainBody').html(msg);
            },
            error: function(){
                alert('failure');
            }
        });
    });
</script>

Your

data:"someValue="+$_POST['someValue'],

Should be

data:"someValue="+<?php echo $_POST['someValue'];?>,,

or

data:"someValue=<?php echo $_POST['someValue'];?>", if the $_POST['someValue'] is a string as it will make the javscript error out if you dont put it in quotes.

 $(document).on("pageinit",function(){

did not work.

 $(document).ready(function(){

did.