#Rest/Spread Properties S4

#Object Rest/Spread Properties for ECMAScript

ECMAScript 6 introduces rest elements for array destructuring assignment and spread elements for array literals.

This proposal introduces analogous rest properties for object destructuring assignment and spread properties for object literals.

#Specification

Specification

#Rest Properties

Rest properties collect the remaining own enumerable property keys that are not already picked off by the destructuring pattern. Those keys and their values are copied onto a new object.

let { x, y, ...z } = { x: 1, y: 2, a: 3, b: 4 };
x; // 1
y; // 2
z; // { a: 3, b: 4 }

#Spread Properties

Spread properties in object initializers copies own enumerable properties from a provided object onto the newly created object.

let n = { x, y, ...z };
n; // { x: 1, y: 2, a: 3, b: 4 }

#Transpilers

Babel

Bublé

JSTransform

TypeScript

#Status of this Proposal

It is a Stage 4 proposal for ECMAScript.

#Known Issues

This proposal only iterates over own properties. See why this matters.