spread-rest.js

const bleh = ['b', 'c', 'd'];

// Want arr === ['a', 'b', 'c', 'd']

const arr = [ 'a', ...bleh ]; // ['a', 'b', 'c', 'd']

// Also for objects

const basicInfo = {
  name: 'Person',
  age: 21,
};

const person = {
  ...someValues,
  occupation: 'Belt Wearer',
}; // { name: 'Person', age: 21, occupation: 'Belt Wearer' };

// Function args can be directly destructured. NOTE that all of these functions below return the same object. Also note that
// I use const more than once for the same var which would be an error in real code. 

// Take 1
const Person = (opts) => {
  const age = opts.age;
  const name = opts.name;
  return {
    age,
    name,
    occupation: 'Freelancer',
  };
};

// Take 2
const Person = (opts) => {
  const { age, name } = opts;
  return {
    age,
    name,
    occupation: 'Freelancer',
  };
};

// Take 3
const Person = ({ age, name }) => {
  return {
    age,
    name,
    occupation: 'Freelancer',
  };
};

// Take 3 (another version)
const Person = (opts) => {
  return {
    ...opts,
    occupation: 'Freelancer',
  };
};

// Take 4 :D
const Person = (opts) => ({ ...opts, occupation: 'Freelancer' });