new TransformStream([transformer[, writableStrategy[, readableStrategy]]])

新增于: v16.5.0

transformer <Object>
- start <Function> 创建 TransformStream 时立即调用的用户定义函数。
  
  ¥start <Function> A user-defined function that is invoked immediately when the TransformStream is created.
  - controller <TransformStreamDefaultController>
  - 返回：undefined 或用 undefined 实现的 promise
    
    ¥Returns: undefined or a promise fulfilled with undefined
- transform <Function> 一个用户定义的函数，它接收并可能修改写入 transformStream.writable 的数据块，然后再将其转发到 transformStream.readable。
  
  ¥transform <Function> A user-defined function that receives, and potentially modifies, a chunk of data written to transformStream.writable, before forwarding that on to transformStream.readable.
  - chunk <any>
  - controller <TransformStreamDefaultController>
  - 返回：undefined 兑现的 promise。
    
    ¥Returns: A promise fulfilled with undefined.
- flush <Function> 在 TransformStream 的可写端关闭之前立即调用的用户定义函数，表示转换过程结束。
  
  ¥flush <Function> A user-defined function that is called immediately before the writable side of the TransformStream is closed, signaling the end of the transformation process.
  - controller <TransformStreamDefaultController>
  - 返回：undefined 兑现的 promise。
    
    ¥Returns: A promise fulfilled with undefined.
- readableType <any> readableType 选项保留供将来使用，并且必须是 undefined。
  
  ¥readableType <any> the readableType option is reserved for future use and must be undefined.
- writableType <any> writableType 选项保留供将来使用，并且必须是 undefined。
  
  ¥writableType <any> the writableType option is reserved for future use and must be undefined.
writableStrategy <Object>
- highWaterMark <number> 应用背压之前的最大内部队列大小。
  
  ¥highWaterMark <number> The maximum internal queue size before backpressure is applied.
- size <Function> 一个用户定义的函数，用于标识每个数据块的大小。
  
  ¥size <Function> A user-defined function used to identify the size of each chunk of data.
  - chunk <any>
  - 返回：<number>
    
    ¥Returns: <number>
readableStrategy <Object>
- highWaterMark <number> 应用背压之前的最大内部队列大小。
  
  ¥highWaterMark <number> The maximum internal queue size before backpressure is applied.
- size <Function> 一个用户定义的函数，用于标识每个数据块的大小。
  
  ¥size <Function> A user-defined function used to identify the size of each chunk of data.
  - chunk <any>
  - 返回：<number>
    
    ¥Returns: <number>