demo.ts

const origData = [
    {
        uid:123123,
        displayName: "user1",
        email: null,
        emailVerified: false,
        isAnonymous: false,
        photoURL: "http://gooooooo.com/123123jiji",
        nestedData: {
            admin: false,
            address: "123 Baker st, London, UK",
            age: null,
            gender: "neutral"
        }
    },
    {
        uid:45345345,
        displayName: "user2",
        email: null,
        emailVerified: false,
        photoURL: "http://gooooooo.com/123123jiji",
        accountType: "google",
        createdTime: 4234335542,
        nestedData: {}
    },
    {
        uid:87897,
        displayName: "user34234234",
        email: "[email protected]",
        emailVerified: true,
        isAnonymous: true,
        photoURL: "http://gooooooo.com/123123jiji",
        accountType: "google",
        createdTime: 234252555,
        nestedData: {
            admin: false,
            address: null,
            age: 34,
            gender: "male"
        }
    },
]

export interface AdminUser {
  uid?: string
  displayName?: string
  email?: string
  emailVerified?: boolean
  isAnonymous?: boolean
  photoURL?: string
}

let adminList = origData.map((data) => {
  return data as unknown as AdminUser
})

// my expecting after force casting
adminList = [
    {
        uid:123123,
        displayName: "user1",
        email: null,
        emailVerified: false,
        isAnonymous: false,
        photoURL: "http://gooooooo.com/123123jiji",
    },
    {
        uid:45345345,
        displayName: "user2",
        email: null,
        emailVerified: false,
        isAnonymous: null,
        photoURL: "http://gooooooo.com/123123jiji",
    },
    {
        uid:87897,
        displayName: "user34234234",
        email: "[email protected]",
        emailVerified: true,
        isAnonymous: true,
        photoURL: "http://gooooooo.com/123123jiji",
    },
]