filehandle.read(buffer[, options])

• buffer <Buffer> | <TypedArray> | <DataView> 将填充读取的文件数据的缓冲区。
• options <Object>
  • offset <integer> 缓冲区中开始填充的位置。 默认值: 0
  • length <integer> 读取的字节数。 默认值: buffer.byteLength - offset
  • position <integer> 从文件开始读取数据的位置。 如果为 null，则将从当前文件位置读取数据，并将更新该位置。 如果 position 是整数，则当前文件位置将保持不变。 默认值:: null
• 返回: <Promise> 成功时将使用具有以下两个属性的对象履行：
  • bytesRead <integer> 读取的字节数
  • buffer <Buffer> | <TypedArray> | <DataView> 对传入的 buffer 参数的引用。

从文件中读取数据，并将其存储在给定的缓冲区中。

如果未同时修改文件，当读取的字节数为零时，则到达文件末尾。

• buffer <Buffer> | <TypedArray> | <DataView> A buffer that will be filled with the file data read.
• options <Object>
  • offset <integer> The location in the buffer at which to start filling. Default: 0
  • length <integer> The number of bytes to read. Default: buffer.byteLength - offset
  • position <integer> The location where to begin reading data from the file. If null, data will be read from the current file position, and the position will be updated. If position is an integer, the current file position will remain unchanged. Default:: null
• Returns: <Promise> Fulfills upon success with an object with two properties:
  • bytesRead <integer> The number of bytes read
  • buffer <Buffer> | <TypedArray> | <DataView> A reference to the passed in buffer argument.

Reads data from the file and stores that in the given buffer.

If the file is not modified concurrently, the end-of-file is reached when the number of bytes read is zero.