编译前

    1. enum CompassDirection {
    2.   North,
    3.   East,
    4.   South,
    5.   West
    6. }
    8. const startingDirection = CompassDirection.East

    编译后，很巧妙的写法

    1. var CompassDirection;
    2. (function(CompassDirection) {
    3.   CompassDirection[CompassDirection['North'] = 0] = 'North';
    4.   CompassDirection[CompassDirection['East'] = 1] = 'East';
    5.   CompassDirection[CompassDirection['South'] = 2] = 'South';
    6.   CompassDirection[CompassDirection['West'] = 3] = 'West';
    7. })(CompassDirection || CompassDirection = {});
    9. const staringDirection = CompassDirection.East