Rest/Spread Properties for ECMAScript
HTML Shell
Latest commit a1d33ff Oct 6, 2016 @sebmarkbage committed on GitHub Merge pull request #19 from maxdow/patch-1
Updated stage to 3 in the Readme

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.



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 }




Status of this Proposal

It is a Stage 3 proposal for ECMAScript.

Known Issues

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