_onSuccess(response, status, headers) {
            this.isReady = false;
            this.isUploading = false;
            this.isUploaded = true;
            this.isSuccess = true;
            this.isCancel = false;
            this.isError = false;
            this.progress = 100;
            this.index = null;
            this.onSuccess(response, status, headers);
        }
Inner callback
@param {*} response
@param {Number} status
@param {Object} headers
@private