The Object keys() method

Object.keys() accepts an object as argument and returns an array of all its (own) enumerable properties.

const car = {
  color: 'Blue',
  brand: 'Ford',
  model: 'Fiesta'
}

Object.keys(car) //[ 'color', 'brand', 'model' ]

I said enumerable properties. This means their internal enumerable flag is set to true, which is the default. Check MDN for more info on this subject.

One use of the Object.keys function is to create a copy of an object that has all the properties of it, except one:

const car = {
  color: 'blue',
  brand: 'Ford'
}
const prop = 'color'

const newCar = Object.keys(car).reduce((object, key) => {
  if (key !== prop) {
    object[key] = car[key]
  }
  return object
}, {})

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Published Apr 12, 2019