immutable-object-array-property.md

const droid = {
  name: 'R2-D2',
  height: '1.08',
  colors: ['blue', 'silver']
}

const newDroid = {
  ...droid,
  colors: [...droid.colors, 'white']
}

//the original object is not updated
console.log(droid)
// [object Object] {
//   colors: ['blue', 'silver'],
//   height: '1.08',
//   name: 'R2-D2'
// }

// we created a totally new object
console.log(newDroid)
// [object Object] {
//   colors: ['blue', 'silver', 'white'],
//   height: '1.08',
//   name: 'R2-D2'
// }