ReadableStreamDefaultReader()
constructor creates and returns a
ReadableStreamDefaultReader
对象实例。
注意
: You generally wouldn't use this constructor manually; instead, you'd use the
ReadableStream.getReader()
方法。
var readableStreamDefaultReader = new ReadableStreamDefaultReader(stream);
ReadableStream
to be read.
An instance of the
ReadableStreamDefaultReader
对象。
stream
parameter is not a
ReadableStream
, or it is already locked for reading by another reader.
In the following simple example, a previously-created custom
ReadableStream
is read using a
ReadableStreamDefaultReader
created using
getReader()
. (see our
Simple random stream example
for the full code). Each chunk is read sequentially and output to the UI, until the stream has finished being read, at which point we return out of the recursive function and print the entire stream to another part of the UI.
function fetchStream() {
const reader = stream.getReader();
let charsReceived = 0;
// read() returns a promise that resolves
// when a value has been received
reader.read().then(function processText({ done, value }) {
// Result objects contain two properties:
// done - true if the stream has already given you all its data.
// value - some data. Always undefined when done is true.
if (done) {
console.log("Stream complete");
para.textContent = result;
return;
}
// value for fetch streams is a Uint8Array
charsReceived += value.length;
const chunk = value;
let listItem = document.createElement('li');
listItem.textContent = 'Received ' + charsReceived + ' characters so far. Current chunk = ' + chunk;
list2.appendChild(listItem);
result += chunk;
// Read some more, and call this function again
return reader.read().then(processText);
});
}
| 规范 | 状态 | 注释 |
|---|---|---|
|
流
The definition of 'ReadableStreamDefaultReader()' in that specification. |
实时标准 | 初始定义。 |
| 桌面 | 移动 | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
ReadableStreamDefaultReader()
构造函数
|
Chrome ? | Edge ? |
Firefox
65
|
IE ? | Opera ? | Safari ? | WebView Android ? | Chrome Android ? |
Firefox Android
65
|
Opera Android ? | Safari iOS ? | Samsung Internet Android ? |
完整支持
兼容性未知
实验。期望将来行为有所改变。
用户必须明确启用此特征。
ReadableStreamDefaultReader
ReadableStreamDefaultReader()