Доступ к содержимому iframe

$(document).ready(function(){ 
 
$('#hiddenframe').load(function(){ 
    var iframe = $('#hiddenframe').contents().find("#frame_test_div").html(); 
    console.log('Ответ '+iframeDocument); 
 
}); 
}); 
  

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script> 
 
<form enctype="multipart/form-data" action="" method="post" name="loadavatar" target="hiddenframe"> 
<input type=hidden name=MAX_FILE_SIZE value=10485760> 
<input id=avatarfile name=filename type=file> 
<input type="submit" value="Загрузить" name="Subm" id="uploadButton"> 
</form> 
 
<iframe id="hiddenframe" name="hiddenframe"> 
<div id="frame_test_div">фрейм</div> 
<? 
if (isset($_POST['Subm'])) { 
$upload_file = $_FILES["filename"]["tmp_name"]; 
list ($validate, $width, $height, $filetype) = validate($upload_file); 
 
if ($validate == 'ok') { 
 
    $filename = new_name($user_id); 
    echo 'Файл: '. $filename; 
    add_img$upload_file, '../img/temp', $filename, $filetype); 
 
    } 
} 
?> 
</iframe>