javascript async / await 不能与 fetch 结合使用
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async / await not working in combination with fetch
提问by Jeanluca Scaljeri
I'm trying to use ES7 async/ awaittogether with fetch. I know I'm close but I can't get it to work. Here is the code:
我正在尝试将 ES7 async/await与fetch. 我知道我很接近但我无法让它工作。这是代码：
class Bar {
async load() {
let url = 'https://finance.yahoo.com/webservice/v1/symbols/goog/quote?format=json';
try {
response = await fetch(url);
return response.responseText;
} catch (e) {
return e.message;
}
}
}
which I use as follows:
我使用如下：
let bar = new Bar();
bar.load().then(function (val) {
console.log(val);
});
For some reason I always get into the catchwith the message
出于某种原因，我总是进入catch消息
response is not defined
Any suggestions what I do wrong ?
任何建议我做错了什么？
UPDATE: As suggested in the comments, it might be an issue with fetch, so I tried a simplified (ES5) version:
更新：正如评论中所建议的，这可能是一个问题fetch，所以我尝试了一个简化的（ES5）版本：
<!doctype html>
<html>
<head>
<script>
var url = 'https://finance.yahoo.com/webservice/v1/symbols/goog/quote?format=json';
fetch(url, {method: 'get', mode: 'cors'}).then(function (response) {
console.log(response.responseText);
});
</script>
<head>
<body></body>
<html>
And still doesn't work :( However, if I replace fetch it works:
仍然不起作用:(但是，如果我替换 fetch ，它会起作用：
var request = new XMLHttpRequest();
request.open("GET", url, false);
request.send(null);
console.log(request.responseText);
采纳答案by Bergi
You forgot to declare responseas a variable. Class code is always strict code, and you won't get away with assigning to implictly global variables. Instead, it throws a ReferenceError.
您忘记声明response为变量。类代码始终是严格的代码，您将无法逃避分配给隐式全局变量。相反，它会抛出一个ReferenceError.
Apart from that, Responseobjects don't have a responseTextproperty like a XHR, they do have a .text()method that waits for the body to be received and returns a promise.
除此之外，Response对象没有responseText像 XHR这样的属性，它们确实有一个.text()方法来等待主体被接收并返回一个承诺。
class Bar {
async load() {
let url = 'https://finance.yahoo.com/webservice/v1/symbols/goog/quote?format=json';
try {
let response = await fetch(url);
// ^^^^
return await response.text();
// ^^^^^^
} catch (e) {
return e.message;
}
}
}
