mutable-object-array-property.md

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

const newDroid = { ...droid }

newDroid.colors.push('white')

//the original object is updated by push of new color
console.log(droid)
// [object Object] {
//   colors: ['blue', 'silver', 'white'],
//   height: '1.08',
//   name: 'R2-D2'
// }

// we created a new object with the same references of nested objects/arrays
console.log(newDroid)
// [object Object] {
//   colors: ['blue', 'silver', 'white'],
//   height: '1.08',
//   name: 'R2-D2'
// }