Firebase Stored Data With ${res.user.uid} Instead Of Userid

Firebase stored data with ${res.user.uid} instead of userid .Please advise solution how to store user with userid

try{
  const res= await this.afAuth.auth.createUserWithEmailAndPassword(username,password)
  this.afstore.doc('users/${res.user.uid}').set({
    username
  })

  this.user.setUser({
    username,
    uid:res.user.uid
  })

You are using template literals but instead of using back-tips you use normal single quotes.

As explained in the doc:

Template literals are enclosed by the back-tick character instead of double or single quotes.