const users =
[ {username: 'lubien',       name: 'João'    }
, {username: 'rian-vergara', name: 'Rian'    }
, {username: 'leochrisis',   name: 'Leonardo'}
]

const usernames = users.map(user => user.username)
const names = users.map(user => user.name)

console.log(usernames)
// [ 'lubien', 'rian-vergara', 'leochrisis' ]
console.log(names)
// [ 'João', 'Rian', 'Leonardo' ]