response.filesize中react-native-image-picker返回的文件大小是什么格式？是字节还是位？
检查下面的代码：

try{  
  let options = {
    mediaType: 'photo',
    maxWidth: 1280,
    maxHeight: 720,
    quality: .5,
    includeBase64:true
  };

   const reso = launchImageLibrary(options, (response) => {
    console.log('Response = ', response);

    if (response.didCancel) {
      alert('User cancelled camera picker');
      return;
    } else if (response.errorCode == 'camera_unavailable') {
      alert('Camera not available on device');
      return;
    } else if (response.errorCode == 'permission') {
      alert('Permission not satisfied');
      return;
    } else if (response.errorCode == 'others') {
      alert(response.errorMessage);
      return;
    }
    // console.log('base64 -> ', response.assets[0].base64);
    console.log('uri -> ', response.assets[0].uri);
    console.log('width -> ', response.assets[0].width);
    console.log('height -> ', response.assets[0].height);
    console.log('fileSize -> ', response.assets[0].fileSize);
    console.log('type -> ', response.type);
    console.log('fileName -> ', response.fileName);
    console.log("base 64 length ",response.assets[0].base64.length)
    setCompressedImage(response.assets[0].uri)
   
  });

我想知道这里的文件大小。
response.assets[0].fileSize的值为484908。是字节还是什么？