Node.JSv8的5个新特性：支持string padding与async/await和object参数省略

// String.prototype.padStart(targetLength [, padString])
'hello'.padStart(10); // '     hello'
'hello'.padStart(10, '0'); // '00000hello'
'hello'.padStart(); // 'hello'
'hello'.padStart(6, '123'); // '1hello'
'hello'.padStart(3); // 'hello'
'hello'.padStart(3, '123'); // 'hello';

// String.prototype.padEnd(targetLength [, padString])
'hello'.padEnd(10); // 'hello     '
'hello'.padEnd(10, '0'); // 'hello00000'
'hello'.padEnd(); // 'hello'
'hello'.padEnd(6, '123'); // 'hello1'
'hello'.padEnd(3); // 'hello'
'hello'.padEnd(3, '123'); // 'hello';

function foo(
  a,
  b,
  c, // this threw a Parse Error before Node 8
) { … }

foo(
  ‘a’,
  ‘b’,
  ‘c’, // this threw a Parse Error before Node 8
);

const co = require('co');
const fetch = require('node-fetch');

function * getUser(username) {
  const res = yield fetch(`https://api.github.com/users/${username}`);
  const json = yield res.json();
  return json;
}

function * start() {
  const user = yield getUser('github');
  console.log(user); // prints out info about ‘github’ user on GitHub
}

co(start);

const fetch = require('node-fetch');

async function getUser(username) {
  const res = await fetch(`https://api.github.com/users/${username}`);
  const json = await res.json();
  return json;
}

async function start() {
  const user = await getUser('github');
  console.log(user); // prints out info about ‘github’ user on GitHub
}

start();

function latex(strings) {
  // ...
}

latex`
\document{article}
\usepackage{somepackage}
`
// \document{article} works on previous Node versions
// \usepackage{somepackage} will only work on Node 8 due to ‘\u’ special character

const foo = { a: 1, b: 2, c: 3 };
const { a, ...rest } = foo;
console.log(rest); // { b: 2, c: 3 }

const foo = { a: 1, b: 2, c: 3 };
const bar = { d: 4, e: 5 };
const baz = {};

const qux = { ...foo, ...bar, ...baz };
console.log(qux); // { a: 1, b: 2, c: 3, d: 4, e: 5 }