Question

这是我的网页

Set sht = ActiveSheet
For Each co In sht.ChartObjects
    co.Activate
    For Each sc In ActiveChart.SeriesCollection
        temp = sc.Formula
        'Counting commas in formula
        counter = Len(temp) - Len(Replace(temp, ",", ""))
        'If commas were 3 then 4 params
        If counter = 3 Then
            sc.Formula = "=SERIES(,,1,1)"
        'If commas were 4 then 5 params
        ElseIf Count = 4 Then
            sc.Formula = "=SERIES(,,,1,1)"
        End If

        sc.Formula = temp

    Next sc
Next co

假设我已经登录了用户。当我在控制台中加载页面时，我得到<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <meta http-equiv="X-UA-Compatible" content="IE=edge"> <meta name="viewport" content="width=device-width, initial-scale=1"> <title>Calcolo Diliuzioni</title> </head> <body> <h1>My app</h1>  <script src="https://apis.google.com/js/platform.js" async defer></script>  <script src="https://www.gstatic.com/firebasejs/live/3.0/firebase.js"></script> <script> // Initialize Firebase var config = { apiKey: "", authDomain: "", databaseURL: "", storageBucket: "", }; firebase.initializeApp(config); </script> <script type="text/javascript"> var user = firebase.auth().currentUser; if (user) { console.log(user); } else { console.log(user); } </script> </body> </html>。虽然我期望拥有当前用户的对象。

如果我在浏览器控制台中运行相同的代码

null

我能够获取当前用户的对象。

我认为var user = firebase.auth().currentUser; if (user) { console.log(user); } else { console.log(user); }有一些异步行为。解决问题的正确方法是什么？我应该在firebase.initializeApp(config);函数上使用承诺吗？一种回调..

Answer 1

初始化应用是同步的。但是，确定当前用户状态是异步的。确定当前身份验证状态的正确方法是使用观察者： https://firebase.google.com/docs/auth/web/manage-users

firebase.auth().onAuthStateChanged(function(user) {
  if (user) {
    // User is signed in and currentUser will no longer return null.
  } else {
    // No user is signed in.
  }
});

Answer 2

我将两种方法结合在一起：

function canActivate(){
    return new Promise(resolve => {
        if (firebase.auth().currentUser) {
            resolve(true);
        } else {
            const unsubscribe = firebase.auth().onAuthStateChanged(function (user) {
                unsubscribe();
                if (user) {
                    resolve(true);
                } else {
                    resolve(false);
                }
            });
        }
    });
}

在SPA，如果用户已登录且用户可以转到任何页面，请firebase.auth().currentUser == true。但是如果用户重新加载页面，请获取firebase.auth().currentUser == false。用户需要等待firebase.initializeApp(config);完成，所以添加 firebase.auth().onAuthStateChanged等待init完成。

firebase.initializeApp回调/承诺？

2 个答案: