jQuery ajax php图像加载

Question

我有一个有2个输入的表单。文本和文件上传。我想发送数据到ajax，然后在php中创建一个带有某个名称的文件。我有代码，但它不能工作。

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
</head>
<body>
<script src="http://code.jquery.com/jquery-1.8.3.js"></script>

<form id="form">
    <input type="text" name="name"><br>
    <input id="photo" name="photo" accept="image/jpeg" type="file" placeholder="Фото"><br><br>
    <input name="submit" type="submit" value="Load">
</form>
<script src="ajax.js"></script>
</body>
</html>

AJAX：

$(document).ready(function() {
    $ = jQuery;

});

$(".photo input[name='photo']").change(function() {
    var reader = new FileReader();
    reader.onload = function (e) {
        $('.photo img').attr('src', e.target.result);
    }
    reader.readAsDataURL(this.files[0]);
});

$("#form").submit(function(e) {
    e.preventDefault();

    var photo = document.getElementById('photo');
    if(photo.files.lenght) {
        if(photo.files[0].size > 500000) {
            alert("Ошибка: Изображение не должно превышать размер в 500кб.");
            return;
        }
    }

    var formData = new FormData($(this)[0]);

    $.ajax({
        type: "POST",
        url: "ajax.php",
        data: formData,
        async: true,
        cache: false,
        contentType: false,
        processData: false,
        success: function(data) {

            } 
        },
);
});

PHP：

<?php   
    function check_file_uploaded_name($filename) {
        return preg_match("`^[-0-9A-Z_\.]+$`i", $filename) ? true : false;
    }

    function check_file_uploaded_length ($filename){
        return (mb_strlen($filename,"UTF-8") > 225) ? false : true;
    }   
    if($_SERVER['REQUEST_METHOD'] === 'POST') { 

        if(!$_FILES['photo']['error']) {        
            $name = $_FILES['photo']['name'];   
                if(!check_file_uploaded_name($name) || !check_file_uploaded_length($name)) {
                    die(json_encode(array("error" => "Wrong file name"), JSON_UNESCAPED_UNICODE));          
                }

                if($_FILES['photo']['size'] > 500000) {
                    die(json_encode(array("error" => "Wrong file size"), JSON_UNESCAPED_UNICODE));          
                }           

                if (!file_exists("/photo")) {               
                    mkdir("/photo", 0777, true);            
                }   

                move_uploaded_file($_FILES['vac-photo']['tmp_name'], "/photo/1.jpg");       
        }   
    }
?>

什么都没发生。:(