const scores = [85, 92, 78, 90];  
const student = {
  name: 'Jordan',
  grade: 'A',
  ...{ courses: ['Math', 'Science'] },
  scores,
  average: function() { return this.scores.reduce((a, b) => a + b) / this.scores.length }
};

const { name, ...details } = student;
const [first, ...rest] = scores;

console.log(details.scores[0], rest[0]);