JS: ECMAScript 2017

New object methods

• JS: Object.entries
• JS: Object.values
• JS: Object.getOwnPropertyDescriptors

New string methods

• JS: String.prototype.padStart
• JS: String.prototype.padEnd

Allow one trailing comma in syntax

now allow one trailing comma in object literals, function parameters, named imports, named exports.

before, it was allowed in array literal only.

// deno-fmt-ignore
const xx = { a: 0, b: 0, };
console.log(xx);
// { a: 0, b: 0 }

// repeated trailing comma is syntax error
const xx = { a: 0, b: 0, ,};

// deno-fmt-ignore
function ff(x,) { return x + 1; }
console.log(ff(3) === 4);

• JS: Create Array

keywords: async, await

• async keyword for functions and await keyword.

Async functions improve the asynchronous programming experience by providing syntax for promise-returning functions.

Shared Memory and Atomics

Shared Memory and Atomics introduce a new memory model that allows multi-agent programs to communicate using atomic operations that ensure a well-defined execution order even on parallel CPUs.