TypeError：jQuery（...）。ajaxForm不是函数magento

Question

我想在magento前端上传图片并通过ajax显示。但是我收到此错误TypeError: jQuery(...).ajaxForm is not a function，这会在定义文件夹中上传图片并在前端显示时产生问题。

这是我的代码：

<script type="text/javascript" src="<?php echo Mage::getBaseUrl();?>/skin/frontend/rwd/default/js/jquery.form.js"></script>

                        <form id="imageform" method="post" enctype="multipart/form-data" action='<?php echo $this->getUrl('productcustomize/index/uploadimage/'); ?>'>

                           <div class="right">

                                    <h3>UPLOAD YOUR PICTURES</h3>                                    
                                    <h4>Side Profile</h4>
                                    <span>Sample Picture</span>
                                   <input type="file" name="photoimg" id="photoimg" />                                

                                </div>
                                <div id='preview'></div>

                        </form>
<script type="text/javascript" >
 jQuery(document).ready(function() { 

            jQuery('#photoimg').on('change', function()         { 
                       jQuery("#preview").html('');
                jQuery("#preview").html('<img src="<?php echo Mage::getBaseUrl();?>/skin/frontend/base/default/lotusbreath/onestepcheckout/images/loader.gif" alt="Uploading...."/>');
            jQuery("#imageform").ajaxForm({
                        data: jQuery(this).serialize(),
                        target: '#preview'
        }).submit();

            });
        }); 

</script>

IndexController.php

 public function uploadimageAction()
     {

        $path = getcwd()."/media/sideprofile/";

        $valid_formats = array("jpg", "png", "gif", "bmp");
        if(isset($_POST) and $_SERVER['REQUEST_METHOD'] == "POST")
        {
            $name = $_FILES['photoimg']['name'];
            $size = $_FILES['photoimg']['size'];

            if(strlen($name))
                {
                    list($txt, $ext) = explode(".", $name);
                    if(in_array($ext,$valid_formats))
                    {
                    if($size<(1024*1024))
                        {
                            $actual_image_name = md5(date('Y-m-d H:i:s')).".".$ext;
                            $tmp = $_FILES['photoimg']['tmp_name'];
                            if(move_uploaded_file($tmp, $path.$actual_image_name))
                                {

                                    $_SESSION['custom_image'][] = $actual_image_name;
                                    $custom_image_data = $_SESSION['custom_image'];
                                    foreach($custom_image_data as $key=>$img){
                                        if($img !=""){
                                        $resizeimg = Mage::getBaseUrl().'/media/sideprofile/uploads/'.$img;

                                      }
                                    }
                                }
                            else
                                echo "failed";
                        }
                        else
                        echo "Image file size max 1 MB";                   
                        }
                        else
                        echo "Invalid file format..";   
                }

            else
                echo "Please select image..!";

            exit;
        }
     }