WritableStreamDefaultWriter.ready
Experimental: 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 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 |
---|
Streams Standard # ref-for-default-writer-ready⑨ |
Browser compatibility
BCD tables only load in the browser