为什么此代码无法执行“获取"? [英] Why does this code fail to execute 'fetch'?
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问题描述
我正在使用 Service Worker 处理推送通知.我正在使用 XHR(Ajax) 方法来获取通知,这里是 service-worker.js 的代码片段:
I'm working on push notifications using service workers. I'm using the XHR(Ajax) approach to get my notification, here is a code snippet of service-worker.js:
var API_ENDPOINT = new Request('/getNotification', {
redirect: 'follow'});
event.waitUntil(
fetch(API_ENDPOINT, {credentials: 'include' })
.then(function(response) {
console.log(response);
if (response.status && response.status != 200) {
// Throw an error so the promise is rejected and catch() is executed
throw new Error('Invalid status code from API: ' +
response.status);
}
// Examine the text in the response
return response.json();
})
.then(function(data) {
console.log('API data: ', data);
var title = 'TEST';
var message = data['notifications'][0].text;
var icon = data['notifications'][0].img;
// Add this to the data of the notification
var urlToOpen = data['notifications'][0].link;
var notificationFilter = {
tag: 'Test'
};
var notificationData = {
url: urlToOpen,
parsId:data['notifications'][0].parse_id
};
if (!self.registration.getNotifications) {
return showNotification(title, message, icon, notificationData);
}
})
.catch(function(err) {
console.error('A Problem occured with handling the push msg', err);
var title = 'An error occured';
var message = 'We were unable to get the information for this ' +
'push message';
return showNotification(title, message);
})
);
这段代码在我第一次运行 curl 时工作正常,但第二次在控制台中出现错误:
This code works fine the first time I run the curl, but the second time I got an error in the console:
Failed to execute 'fetch' on 'ServiceWorkerGlobalScope': Cannot construct a Request with a Request object that has already been used
这是什么意思?
推荐答案
问题是 API_ENDPOINT
已经被 fetch()
消费了.每次传递它时都需要一个新的请求对象来获取所以 clone 使用前:
The problem is that API_ENDPOINT
has already consumed by the fetch()
. You need a fresh request object each time you pass it to fetch so clone it before using it:
fetch(API_ENDPOINT.clone(), { credentials: 'include' })...
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