Tutorial

Object Rest and Spread in TypeScript

TypeScript

While this tutorial has content that we believe is of great benefit to our community, we have not yet tested or edited it to ensure you have an error-free learning experience. It's on our list, and we're working on it! You can help us out by using the "report an issue" button at the bottom of the tutorial.

TypeScript 2.1 brings us object rest & spread to easily destructure, make shallow copies and merge objects into new ones.

Object Spread

Create shallow copy of objects:

const names = {cat: 'Bob', dog: 'Fred', alligator: 'Benedict'};

const newNames = { ...names };

console.log(newNames.cat); // Bob

You can merge multiple objects into a new object:

const names1 = {cat: 'Bob'};
const names2 = {dog: 'Fred', alligator: 'Benedict'};

const newNames = { ...names1, ...names2 };

console.log(newNames.alligator); // Benedict

You can add new properties too, along with using a spread:

const names = {cat: 'Bob', dog: 'Fred', alligator: 'Benedict'};

const newNames = { ...names, hamster: 'Jude' };

console.log(newNames.hamster); // Jude

Note that if a property ends up being inserted multiple times, the last one in wins:

const names = {cat: 'Bob', dog: 'Fred', alligator: 'Benedict'};

const newNames = { dog: 'Skip', ...names };

console.log(newNames.dog); // Fred

Object Rest

Similar to what we can already do in pure JavaScript with object destructuring, rest brings us something that’s in the pipelines for ES2017:

const names = {cat: 'Bob', dog: 'Fred', alligator: 'Benedict'};

const { cat, ...otherAnimals } = names;

console.log(cat); // Bob
console.log(otherAnimals); // {dog: 'Fred', alligator: 'Benedict'}
Creative Commons License