ES6 (1/7)
List all the new things introduced in ES6
    • Arrow functions
    • Classes
    • Modules
    • Promises
    • Template strings
    • Destrcuturing object, array
    • Spread and rest operator
    • Let & const keywords
    • For–of iterator
    • Map + Set + WeakMap + WeakSet
    • Generators
    • Symbols
    • Proxies
    • Improved support for Unicode
    • Tail call optimisation
    • Subclassing built-ins