---

title: "TransformStream: readable property"

short-title: readable

slug: Web/API/TransformStream/readable

page-type: web-api-instance-property

browser-compat: api.TransformStream.readable

---

{{APIRef("Streams")}}{{AvailableInWorkers}}

The **`readable`** read-only property of the {{domxref("TransformStream")}} interface returns the {{domxref("ReadableStream")}} instance controlled by this `TransformStream`. This stream emits the transformed output data.

## Value

A {{domxref("ReadableStream")}}.

## Examples

This example creates a `TransformStream` that converts all input text to uppercase letters. It writes some text to the `writable` stream, then reads the transformed text from the `readable` stream.

```js

const stream = new TransformStream({

transform(chunk, controller) {

controller.enqueue(chunk.toUpperCase());

},

});

// Write data to be transformed

const writer = stream.writable.getWriter();

writer.write("hello ");

writer.write("world");

writer.close();

// Read transformed data

const reader = stream.readable.getReader();

let done = false;

let output = "";

while (!done) {

const result = await reader.read();

if (result.value) {

output += result.value;

}

done = result.done;

}

console.log(output); // HELLO WORLD

```

## Specifications

{{Specifications}}

## Browser compatibility

{{Compat}}