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A WritableStream is the writable property of a TransformStream. On the Workers platform, WritableStream can’t be directly created using the WritableStream constructor.

A typical way to write to a WritableStream is to simply pipe a ReadableStream to it.

.then(() => console.log("All data successfully written!"))
.catch(e => console.error("Something went wrong!", e))

To write to a WritableStream directly, you must use its writer.

const writer = writableStream.getWriter()

See the WritableStreamDefaultWriter documentation for further detail.


  • locked boolean

    • A Boolean value to indicate if the writable stream is locked to a writer.


  • abort(reasonstringoptional) Promise<void>
    • Aborts the stream. This method returns a promise that fulfills with a response undefined. reason is an optional human-readable string indicating the reason for cancellation. reason will be passed to the underlying sink’s abort algorithm. If this writable stream is one side of a TransformStream, then its abort algorithm causes the transform’s readable side to become errored with reason.
  • getWriter() WritableStreamDefaultWriter

    • Gets an instance of WritableStreamDefaultWriter and locks the WritableStream to that writer instance.

See also