This is an experimental technology
Check the Browser compatibility table carefully before using this in production.
The ready
read-only property of the WritableStreamDefaultWriter
interface returns a Promise
that resolves when the desired size of the stream's internal queue transitions from non-positive to positive, signaling that it is no longer applying backpressure.
Syntax
var promise = writableStreamDefaultWriter.ready;
Value
A Promise
.
Example
The following example shows two uses of the ready
property. The first uses ready
to ensure that the WritableStream
is done writing and thus able to receive data before sending a binary chunk. The second also checks whether the the WritableStream
is done writing, but this time because the writing must be finished before the writer can be closed.
function sendMessage(message, writableStream) { // defaultWriter is of type WritableStreamDefaultWriter var defaultWriter = writableStream.getWriter(); var encoder = new TextEncoder(); var encoded = encoder.encode(message, {stream: true}); encoded.forEach(function(chunk) { // Make sure the stream and its writer are able to // receive data. defaultWriter.ready .then(function() { defaultWriter.write(chunk) .then(function() { console.log("Chunk written to sink.); }) .catch(function(err) { console.log("Chunk error: " + err); }); }); // Call ready again to ensure that all chunks are written // before closing the writer. defaultWriter.ready .then(function() { defaultWriter.close() .then(function() { console.log("All chunks written"); }) .catch(function(err) { console.log("Stream error: " + err); }); }); }); }
Specifications
Specification | Status | Comment |
---|---|---|
Streams The definition of 'ready' in that specification. |
Living Standard | Initial definition. |
Browser Compatibility
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
ready | Chrome Full support 59 | Edge Full support 16 | Firefox No support No | IE No support No | Opera Full support 46 | Safari ? | WebView Android Full support 59 | Chrome Android Full support 59 | Firefox Android No support No | Opera Android Full support 43 | Safari iOS ? | Samsung Internet Android Full support 7.0 |
Legend
- Full support
- Full support
- No support
- No support
- Compatibility unknown
- Compatibility unknown
- Experimental. Expect behavior to change in the future.
- Experimental. Expect behavior to change in the future.