ReadableStreamDefaultReader : Object

constructor

Constructors

new ReadableStreamDefaultReader(stream : ReadableStream) : ReadableStreamDefaultReader

Instance Properties

closed : Promise<undefined> readonly

A promise that resolves when the stream closes.

Example:

const stringStream = new ReadableStream({
  start(controller) {
    controller.enqueue('a');
    controller.enqueue('b');
    controller.close();
  }
});

const reader = stringStream.getReader();
reader.closed.then(() => console.log('reader closed'));

let result;
while (!(result = await reader.read()).done) {
  console.log(result.value);
}
console.log('done');

Run

Results:

Instance Methods

cancel([reason : Object]) : Promise<undefined>

Causes the stream to cancel and stop producing new chunks. Causes the UnderlyingSource's cancel method to be called.

Example:

const stringStream = new ReadableStream({
  start(controller) {
    controller.enqueue('a');
    controller.enqueue('b');
    controller.close();
  },
  cancel(reason) {
    console.log(`cancel reason: ${reason}`);
  }
});

const reader = stringStream.getReader();

let result;
while (!(result = await reader.read()).done) {
  console.log(result.value);
  reader.cancel('xyz');
}

Run

Results:

read() : Promise

Promise return type: { value : Object, done : Boolean }

releaseLock() : undefined;

Release the lock on the ReadableStream so another reader can read from the stream.

Example:

const stringStream = new ReadableStream({
  start(controller) {
    controller.enqueue('a');
    controller.enqueue('b');
    controller.close();
  }
});

const reader1 = stringStream.getReader();
const result1 = await reader1.read();
console.log(result1.value);
reader1.releaseLock();

const reader2 = new ReadableStreamDefaultReader(stringStream);
const result2 = await reader2.read();
console.log(result2.value);

Run

Results:

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