Finds the location on the perimeter of a given rectangle that is closest to a given point.

closest_point_on_perimeter_of_rectangle.js

// translated from http://stackoverflow.com/questions/20453545/how-to-find-the-nearest-point-in-the-perimeter-of-a-rectangle-to-a-given-point

function clamp(n,lower,upper) {
  return Math.max(lower, Math.min(upper, n));
}

function getNearestPointInPerimeter(l,t,w,h,x,y) {
  var r = l+w,
      b = t+h;
  
  var x = clamp(x,l,r),
      y = clamp(y,t,b);

  var dl = Math.abs(x-l),
      dr = Math.abs(x-r),
      dt = Math.abs(y-t),
      db = Math.abs(y-b);

  var m = Math.min(dl,dr,dt,db);

  return (m===dt) ? [x,t] :
         (m===db) ? [x,b] :
         (m===dl) ? [l,y] : [r,y];
}

This works great in certain programming languages, but how would I clamp the nearest point on the rectangle when I don't have access to a function that does that? I know how, but it takes more code than I would like and I want to find a simple way to do it.