https://medium.com/@michaelmcshinsky/merging-javascript-objects-b89af94d5b59

merging-javascript-objects-2.js

let obj1 = { firstName: 'John', lastName: 'Doe', email: '[email protected]' };

let obj2 = { email: '[email protected]', phone: '012–345–6789' };

let obj3 = { city: 'Salt Lake City', state: 'Utah' }

let newObj = Object.assign({}, obj1, obj2, obj3);

// {
//  firstName: 'John',
//  lastName: 'Doe',
//  email: '[email protected]',
//  phone: '012–345–6789',
//  city: 'Salt Lake City',
//  state: 'Utah'
// }