ES2015

Practice refactoring with ES2015 features.

CodeRoad

CodeRoad is an open-sourced interactive tutorial platform for the Atom Editor. Learn more at CodeRoad.io.

Setup

• install the tutorial package

  npm install --save coderoad-es2015

• install and run the atom-coderoad plugin

Outline

Let

let allows you to declare variables that are limited in scope to the block, statement, or expression on which it is used.

This is unlike the var keyword, which defines a variable globally, or locally to an entire function regardless of block scope.

var global = true;
let blockScoped = true;

Const

const is block-scoped, much like let statement.

However, the value of a constant cannot change through re-assignment, and it can't be redeclared.

const name = 'Shawn';
name = 'Ben'; // Uncaught TypeError
console.log(name); // Shawn

Note: Atom uses an older version of Chrome that does not fully implement const yet. Const will work in Atom after a few months.

Arrow Functions

An arrow function (=>) expression has a shorter syntax compared to function expressions and lexically binds the this value.

Arrow functions are always anonymous.

// multi-line
const add = (x, y) => {
	return x + y;
};
// single line, auto returns
const subtractOne = x => x - 1;
const getOne = () => 1;

Template Literal

Template literals are string literals allowing embedded expressions. You can use multi-line strings and string interpolation features with them.

Template strings are wrapped in the backtick symbol: '`'. Variables can be put inside of template strings using ${ name } syntax.

let single = `string text`;
let multi = `string text line 1
 string text line 2`;

let template = `string text ${expression} string text`;

Object Literal

A shorthand for writing objects.

const foo = 'something';
const bar = 'else';

// using object literal shorthand
const fooObj = {
  foo, bar
};
// { foo: 'something', bar: 'else'}