php+bootstrap fileinput去上传图片，出错了，求助！

<code>bug：SyntaxError: JSON.parse: unexpected character at line 1 column 1 of the JSON data.
      $("#file-5").fileinput({
        language: 'zh', //设置语言
        uploadUrl:  "{:U('profile/upload')}", // avatar_uploadyou must set a valid URL here else you will get an error __UPLOAD__partner/img
        allowedFileExtensions : ['jpg', 'png','gif'],
        overwriteInitial: false,
        maxFileSize: 1000,
        maxFilesNum: 1,
    
        //allowedFileTypes: ['image', 'video', 'flash'],
        slugCallback: function(filename) {
            alert("aaa");
            return filename.replace('(', '_').replace(']', '_');
        }
    })
     .on("fileuploaded", function (e, data) {
        var res = data.response;
        if (res.state > 0) {
            alert('上传成功');
            alert(res.path);
        }
        else {
            alert('上传失败')
        }
    });
    <form enctype="multipart/form-data">
      <hr>
                <div class="form-group">
                    <input id="file-5" class="file" type="file" multiple data-preview-file-type="any" data-upload-url="#" name="image_data">
                </div>
            </form>
            
            
            后台程序我有public function upload(){ }方法，是php的
            </code>

出错的截图，看着似乎是语法错误，我怀疑是前台fileinput的事件那里出错了，因为后台我只返回一个值做测试，应该没问题的，对fileinput不熟，求助啊！！！谁有例子提供给我参考下也好，谢谢！

回复内容：

<code>bug：SyntaxError: JSON.parse: unexpected character at line 1 column 1 of the JSON data.
      $("#file-5").fileinput({
        language: 'zh', //设置语言
        uploadUrl:  "{:U('profile/upload')}", // avatar_uploadyou must set a valid URL here else you will get an error __UPLOAD__partner/img
        allowedFileExtensions : ['jpg', 'png','gif'],
        overwriteInitial: false,
        maxFileSize: 1000,
        maxFilesNum: 1,
    
        //allowedFileTypes: ['image', 'video', 'flash'],
        slugCallback: function(filename) {
            alert("aaa");
            return filename.replace('(', '_').replace(']', '_');
        }
    })
     .on("fileuploaded", function (e, data) {
        var res = data.response;
        if (res.state > 0) {
            alert('上传成功');
            alert(res.path);
        }
        else {
            alert('上传失败')
        }
    });
    <form enctype="multipart/form-data">
      <hr>
                <div class="form-group">
                    <input id="file-5" class="file" type="file" multiple data-preview-file-type="any" data-upload-url="#" name="image_data">
                </div>
            </form>
            
            
            后台程序我有public function upload(){ }方法，是php的
            </code>

出错的截图，看着似乎是语法错误，我怀疑是前台fileinput的事件那里出错了，因为后台我只返回一个值做测试，应该没问题的，对fileinput不熟，求助啊！！！谁有例子提供给我参考下也好，谢谢！