一个可能的解决办法是利用new Request()
构造函数,然后检查Request.bodyUsed
Boolean
属性
的bodyUsed
属性的获取必须的,如果disturbed
返回true, 否则为false。
,以确定是否流是distributed
实施Body
混入的对象被认为是disturbed
如果 body
为非空并且其stream
disturbed
是。
返回的fetch()
Promise
从.then()
内链接到递归.read()
呼叫的ReadableStream
时Request.bodyUsed
等于true
。
请注意,该方法在字节流式传输到端点时不会读取Request.body
的字节。此外,在任何响应完全返回给浏览器之前,上传可能会完成。
const [input, progress, label] = [
document.querySelector("input")
, document.querySelector("progress")
, document.querySelector("label")
];
const url = "/path/to/server/";
input.onmousedown =() => {
label.innerHTML = "";
progress.value = "0"
};
input.onchange = (event) => {
const file = event.target.files[0];
const filename = file.name;
progress.max = file.size;
const request = new Request(url, {
method: "POST",
body: file,
cache: "no-store"
});
const upload = settings => fetch(settings);
const uploadProgress = new ReadableStream({
start(controller) {
console.log("starting upload, request.bodyUsed:", request.bodyUsed);
controller.enqueue(request.bodyUsed);
},
pull(controller) {
if (request.bodyUsed) {
controller.close();
}
controller.enqueue(request.bodyUsed);
console.log("pull, request.bodyUsed:", request.bodyUsed);
},
cancel(reason) {
console.log(reason);
}
});
const [fileUpload, reader] = [
upload(request)
.catch(e => {
reader.cancel();
throw e
})
, uploadProgress.getReader()
];
const processUploadRequest = ({value, done}) => {
if (value || done) {
console.log("upload complete, request.bodyUsed:", request.bodyUsed);
// set `progress.value` to `progress.max` here
// if not awaiting server response
// progress.value = progress.max;
return reader.closed.then(() => fileUpload);
}
console.log("upload progress:", value);
progress.value = +progress.value + 1;
return reader.read().then(result => processUploadRequest(result));
};
reader.read().then(({value, done}) => processUploadRequest({value,done}))
.then(response => response.text())
.then(text => {
console.log("response:", text);
progress.value = progress.max;
input.value = "";
})
.catch(err => console.log("upload error:", err));
}
@Magix参见[中止取:下一代#447]。(HTTPS:// github上。com/whatwg/fetch/issues/447) – guest271314