Other function features in ES6

Stack

Enums

const directions = {
    UP   : Symbol( 'UP' ),
    DOWN : Symbol( 'DOWN' ),
    LEFT : Symbol( 'LEFT' ),
    RIGHT: Symbol( 'RIGHT' )
};
console.log(directions);
/**
{
    UP: Symbol(UP),
    DOWN: Symbol(DOWN),
    LEFT: Symbol(LEFT),
    RIGHT: Symbol(RIGHT) 
}
 */