How do I remove a property from a JavaScript object?

When working with objects in JavaScript, you might come across situations where a property should be completely removed from an object. To accomplish that, there a few options you have at your disposal:

Set the property to undefined

Setting a property to undefined isn't generally optimal, as the property itself will still be present in the object, albeit undefined. It also mutates the original object, which might be undesired. You might want to use this in cases where you check for the property's value or truthiness but not its presence.

const pet = {
  species: 'dog',
  age: 3,
  name: 'celeste',
  gender: 'female'
};

pet.gender = undefined;
Object.keys(pet); // ['species', 'age', 'name', 'gender']

Use the delete operator

The delete operator is technically the correct way to remove a property from a JavaScript object. Unlike the previous option, delete will completely remove the property from the object, but it will still cause a mutation.

const pet = {
  species: 'dog',
  age: 3,
  name: 'celeste',
  gender: 'female'
};

delete pet.gender;
Object.keys(pet); // ['species', 'age', 'name']

Use object destructuring

Using the spread syntax, (...), you can destructure and assign the object with specific properties omitted to a new object. This trick comes in handy especially if you want to remove a subset of properties instead of just one and has the added benefit of not mutating the original object.

const pet = {
  species: 'dog',
  age: 3,
  name: 'celeste',
  gender: 'female'
};

const { gender, ...newPet } = pet;
Object.keys(pet); // ['species', 'age', 'name', 'gender]
Object.keys(newPet); // ['species', 'age', 'name']