Extract a subtype in a function and return the whole object after modifications-CodePudding

So I have a case where just before I push to my sqlite database I want to clean up the email in my user object. I have a few different functions where i need to do this, like creation of the user and in updates of the user. So considering the case:

export const addUser = (user: CreateUser) => {
  db.prepare(sqlInsertUser).run(cleanEmail(user))
}

export const updateUser = (user: UpdateUser) => {
  db.prepare(sqlUpdateUser).run(cleanEmail(user))
}

type CreateUser = {
  email: string
  password: string
  permissionLevel?: number
}


type UpdateUser = {
  email: string
  password: string
}

Now I'm trying to implement:

const cleanEmail = (user: ?) => {
  user.email = user.email.trim()
  return user
}

But I'm blanking out here, how do i grab both types and return the whole object? What do I put as type?

How can I do this well, even with more types but where all the types contain the email property?

CodePudding user response：

You can take a generic type that must have an email property that is a string:

const cleanEmail = <T extends { email: string }>(user: T) => {
  user.email = user.email.trim()
  return user // return type is inferred as 'T'
};