clockAngle.js

/*
1. calculate angle of hour
2. calculate angle of minutes

# Calculate angle of minutes
1 hour = 60 minutes = 1 full rotation = 360/60 = 6 degree / minute
 ______________________________
|                              |
|angle-of-minutes = 6 * minute |
|                              |
|______________________________|


# Calculate angle of hour
12 hours = 720 minutes = 1 full rotation = 360/720 = 0.5 degree / minute

 ____________________________________________________
|                                                    |
|angle-of-hour = 0.5 * change in minute              |
|              = 0.5 * (60 * hour + minute)          |
|____________________________________________________|

*/

function clockAngle(hour, min){
  var h = 0.5 * (60 * hour + min);
  var m = 6 * min;
  var angle = Math.abs(h - m);
  return (angle > 180) ? 360 - angle : angle;
}

console.log(clockAngle(12,16));