在javascript中使用firebase firestore更新函数中的承诺

我正在尝试在完成用户名更新后立即将用户发送到另一个页面。问题是我不知道什么时候调用location.replace函数，或者在这种情况下如何使用承诺。username.value是新用户名

     //don't worry about the if statment, all it is doing is making sure that the element 
     //that stores the new username is not empty
     if(username.value != ""){
      db.collection("users").doc(doc.id).update({
        "name": username.value
      })  
      //How can I call this as soon as the username is set?
      //location.replace("../pages/homepage.html");
     }

---

你应该在这里找到一些东西：

但你应该这样做：

db.collection("users").doc(doc.id).update({
        "name": username.value
      }) 
      .then(() =>  location.replace("../pages/homepage.html"))