Learn Object Rest and Spread in TypeScript


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'
Muhammad Mubeen

Muhammad Mubeen

Mubeen is a full-stack web & mobile app developer who is very proficient in MEAN.js, Vue, Python, Ionic 4, Flutter, Firebase, ROR, and PHP. He has created multiple mobile and web applications. He is very passionate about sharing his knowledge.

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