Big O in JS: The basic that you need to know, see more at: https://medium.com/p/a5abb45570fa

greaterThan18.js

const people = [
  { name: 'lucy', age: 13}, 
  { name: 'aline', age: 13}, 
  { name: 'john', age: 35}, 
  { name: 'peter', age: 21}, 
  { name: 'james', age: 45}, 
  { name: 'marcela', age: 17}, 
];

const getGreaterThan18 = () => people.filter(person => person.age > 18);
  
//or using destructuring
  
const getGreaterThan18_2 = () => people.filter(({ age }) => age > 18);