writableStream.getWriter()
创建并返回一个新的写入器实例，可用于向 WritableStream 写入数据。
【Creates and returns a new writer instance that can be used to write
data into the WritableStream.】
创建并返回一个新的写入器实例，可用于向 WritableStream 写入数据。
【Creates and returns a new writer instance that can be used to write
data into the WritableStream.】