node.js JavaScript 在 if 语句中等待异步函数
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JavaScript wait for asynchronous function in if statement
提问by pfMusk
I have a function inside an if statement
我在 if 语句中有一个函数
isLoggedin() has an async call.
isLoggedin() 有一个异步调用。
router.get('/', function(req, res, next) {
if(req.isLoggedin()){ <- never returns true
console.log('Authenticated!');
} else {
console.log('Unauthenticated');
}
});
how do i await for isLoggedin() in this if statement?
我如何在这个 if 语句中等待 isLoggedin() ？
here is my isLoggedin function in which im using passport
这是我的 isLoggedin 功能，其中我使用的是护照
app.use(function (req, res, next) {
req.isLoggedin = () => {
//passport-local
if(req.isAuthenticated()) return true;
//http-bearer
passport.authenticate('bearer-login',(err, user) => {
if (err) throw err;
if (!user) return false;
return true;
})(req, res);
};
next();
});
回答by Sterling Archer
I do this exact thing using async/awaitin my games code here
我async/await在这里用我的游戏代码做这件事
Assuming req.isLoggedIn()returns a boolean, it's as simple as:
假设req.isLoggedIn()返回一个布尔值，它很简单：
const isLoggedIn = await req.isLoggedIn();
if (isLoggedIn) {
// do login stuff
}
Or shorthand it to:
或将其简写为：
if (await req.isLoggedIn()) {
// do stuff
}
Make sure you have that inside an asyncfunction though!
确保你在一个async函数中拥有它！
回答by trincot
You could promisifyyour function, like this:
您可以承诺您的功能，如下所示：
req.isLoggedin = () => new Promise((resolve, reject) => {
//passport-local
if(req.isAuthenticated()) return resolve(true);
//http-bearer
passport.authenticate('bearer-login', (err, user) => {
if (err) return reject(err);
resolve(!!user);
})(req, res);
});
And then you can do:
然后你可以这样做：
req.isLoggedin().then( isLoggedin => {
if (isLoggedin) {
console.log('user is logged in');
}
}).catch( err => {
console.log('there was an error:', err);
});
Do not try to keep the synchronous pattern (if (req.isLoggeedin())), as it will lead to poorly designed code. Instead, embracefully the asynchronous coding patterns: anything is possible with it.
不要试图保留同步模式 ( if (req.isLoggeedin()))，因为它会导致代码设计不佳。相反，拥抱完全异步编码模式：一切皆有可能吧。
