Destructuring: object

Destructure objects

by surrounding the left-hand variable with {}

const x = {x: 1}; assert.equal(x, 1);

nested

multiple objects

const magic = {first: 23, second: 42}; const {magic: [second]} = {magic}; assert.equal(second, 42);

object and array

const {z:[x]} = {z: [23, 42]}; assert.equal(x, 42);

array and object

const [,{lang}] = [null, [{env: 'browser', lang: 'ES6'}]]; assert.equal(lang, 'ES6');

interesting

missing refs become undefined

const {z} = {x: 1, z: 2}; assert.equal(z, void 0);

destructure from builtins (string)

const {substr} = 1; assert.equal(substr, String.prototype.substr);

Required Knowledge

• `const` declaration (Block scope)
• basics (Object literal)

Related Katas

Destructuring

• array
• string
• object
• defaults
• parameters
• assign

Difficulty Level

BEGINNER

First Published

30 March 2015

Stats

6 tests to solve