Why setDoc(doc(db, colref, id), {...}) not creat new document in firestore

Question

I have looked up Firestore document and see this method to create new document with customized ID

import { doc, setDoc } from "firebase/firestore"; 

// Add a new document in collection "cities"
await setDoc(doc(db, "cities", "LA"), {
  name: "Los Angeles",
  state: "CA",
  country: "USA"
});

However, when I implement as follow, it returns undefined : doc is not defined

createUserWithEmailAndPassword(auth, txtEmail.value, txtPassword.value).then((userCredential) => {
        setDoc(doc(db, 'users', userCredential.user.uid), {
              email: txtEmail.value,
              name: "nickname",
              password: txtPassword.value,
              on_line: false,
              creat_time: Timestamp.fromDate(new Date())
        }).then((docref) => {
              txtEmail.value = "";
              txtPassword.value = "";
              create_alert("success", userCredential.user + " sign up success");
        });
})

complete file :

import { db, auth } from "./config";
import {collection, getDoc, addDoc, updateDoc, setDoc, Timestamp} from "firebase/firestore";
import {getAuth, createUserWithEmailAndPassword, signInWithEmailAndPassword} from "firebase/auth";

    new_account = () => {
        var txtEmail = document.getElementById('inputEmail');
        var txtPassword = document.getElementById('inputPassword');
        createUserWithEmailAndPassword(auth, txtEmail.value, txtPassword.value).then((userCredential) => {
            console.log("User: " + txtEmail.value + " has succesfully sign up");
            setDoc(doc(db, 'users', userCredential.user.uid), {
                email: txtEmail.value,
                name: "nickname",
                password: txtPassword.value,
                on_line: false,
                creat_time: Timestamp.fromDate(new Date())
            }).then((docref) => {
                txtEmail.value = "";
                txtPassword.value = "";
                create_alert("success", userCredential.user + " sign up success");
            });

Above is most of my file