如何在链式属性表达式中添加前导属性？

const user = {
  profile: {
    name: 'John Doe'
  }
};

const name = user?.profile?.name; // 'John Doe'
const age = user?.profile?.age; // undefined

const user = {
  profile: {
    name: 'John Doe'
  }
};

const name = user && user.profile && user.profile.name; // 'John Doe'
const age = user && user.profile && user.profile.age; // undefined

const user = {
  profile: {
    name: 'John Doe'
  }
};

const name = (user?.profile?.name) ?? 'Unknown'; // 'John Doe'
const age = (user?.profile?.age) ?? 0; // 0

const data = {
  user: {
    profile: {
      settings: {
        theme: 'dark'
      }
    }
  }
};

// 使用可选链操作符
const theme = data?.user?.profile?.settings?.theme; // 'dark'

// 使用逻辑与操作符
const themeWithAnd = data && data.user && data.user.profile && data.user.profile.settings && data.user.profile.settings.theme; // 'dark'

// 使用默认值
const themeWithDefault = (data?.user?.profile?.settings?.theme) ?? 'light'; // 'dark'