Javascript Laravel，ajax base64图像未正确上载

我正在使用DropzoneJS上传我的图像。因此，我要做的是获取dropzoneJS生成的base64URL，然后尝试按如下方式上载：

$( document ).ready(function() {


  var endpoint= $("#endpoint").val();

  var unit = {
    name: '',
    description: '',
    image: '',
    base64Image: '',
    themes: []
  }

  $("#create-unit-btn").on("click", function() {

    unit.name = $("#create-name").val();
    unit.description = $("#create-description").val();
    unit.base64Image = $('#imageDropzone')[0].dropzone.files[0].dataURL;

    var data = {
      '_token': $('meta[name=csrf-token]').attr('content'),
      'unit': unit
    }
    console.log(data);

    $.ajax({
      type: "POST",
      url: endpoint,
      data: data,
      success: function(result){
        console.log(result);
      }
    });
  });

  function validate() {

  }

});

然后使用以下代码上传图像：

public function create( Request $request ) {

    $data = [];
    $code = 200;
    try {

        $unit = new Unit();
        $unit->name = request()->input('unit.name');
        $unit->description = request()->input('unit.description');
        $url = ImageHandler::StoreBase64ToFile($request->input('unit.base64Image'));
        $unit->image = $url;
        $unit->save();
        $data['unit'] = $unit;

    } catch ( \Illuminate\Database\QueryException $e ) {
        // There was an error
        $code = Response::HTTP_UNPROCESSABLE_ENTITY;
        $data = [];
        $data['error'] = ErrorResponse::create($code, $e->getMessage());
    } catch( ModelNotFoundException $e ) {
        return response()->json(['error' => 'invalid operation'], 406);
    }
    return response()->json($data, $code);

}

ImageHandler类执行以下操作：

<?php
namespace App\Libraries;

use Storage;

class ImageHandler {
    /**
     * Store a base64 image into the file system this data has to be
     * sended without any header info like:
     *     data:image/png;base64
     * So the info will look something like iVBORw0....hEUgAAAcQ==
     * @param string $base64Data information
     * @param string $filename the filename if not defined then it generates
     *                         a random name
     * @param string $disk disk location, check Storage documentation of
     *                     laravel, by default is stored on the public folder
     *                     so you'll have to run
     *                         php artisan storage:link
     *                     to make the symbolink links
     * @return string url location of the file
     */
    public static function StoreBase64ToFile($base64Data,
        $filename = null,
        $disk = 'public')
    {
        if (strlen($base64Data) < 10) {
            return null;
        }
        $image = base64_decode($base64Data);
        if ($filename == null) {
            $filename = str_random(16);
            $filename .= '_'.time();
            $filename .= '.png';
        }
        $path = 'images/'.$filename;
        $result = Storage::disk($disk)->put($path, $image, 'public');
        if ($result) {
            $url = Storage::disk($disk)->url($path);
            return $url;
        }
        return null;
    }
}

---

当我存储图像时，是格式错误。为了上传文件没有任何问题，我必须在发送请求之前执行以下操作：
unit.base64Image=unit.base64Image.replace（“数据：image/png；base64，”，”）