Practice optional chaining and nullish coalescing:
let user = {
name: "Alice",
address: { city: "Seattle" }
}
let guest = null
console.log(user?.name) // "Alice"
console.log(guest?.name) // undefined
console.log(user?.address?.city) // "Seattle"
console.log(user?.phone?.number) // undefined
console.log(guest?.name ?? "Anonymous") // "Anonymous"
console.log(user?.name ?? "Anonymous") // "Alice"